Showing papers on "Energy conversion efficiency published in 2014"
TL;DR: Perovskite films received a boost in photovoltaic efficiency through controlled formation of charge-generating films and improved current transfer to the electrodes and low-temperature processing steps allowed the use of materials that draw current out of the perovskites layer more efficiently.
Abstract: Advancing perovskite solar cell technologies toward their theoretical power conversion efficiency (PCE) requires delicate control over the carrier dynamics throughout the entire device. By controlling the formation of the perovskite layer and careful choices of other materials, we suppressed carrier recombination in the absorber, facilitated carrier injection into the carrier transport layers, and maintained good carrier extraction at the electrodes. When measured via reverse bias scan, cell PCE is typically boosted to 16.6% on average, with the highest efficiency of ~19.3% in a planar geometry without antireflective coating. The fabrication of our perovskite solar cells was conducted in air and from solution at low temperatures, which should simplify manufacturing of large-area perovskite devices that are inexpensive and perform at high levels.
5,789 citations
TL;DR: The use of a thin layer of zinc oxide nanoparticles as an electron-transport layer allows flexible perovskite solar cells to be fabricated with a power conversion efficiency as high as 15.7% as mentioned in this paper.
Abstract: The use of a thin layer of zinc oxide nanoparticles as an electron-transport layer allows flexible perovskite solar cells to be fabricated with a power conversion efficiency as high as 15.7%.
2,402 citations
TL;DR: A low-temperature vapor-assisted solution process is demonstrated to construct polycrystalline perovskite thin films with full surface coverage, small surface roughness, and grain size up to microscale, paving the way for high reproducibility of films and devices.
Abstract: Hybrid organic/inorganic perovskites (e.g., CH3NH3PbI3) as light absorbers are promising players in the field of third-generation photovoltaics. Here we demonstrate a low-temperature vapor-assisted solution process to construct polycrystalline perovskite thin films with full surface coverage, small surface roughness, and grain size up to microscale. Solar cells based on the as-prepared films achieve high power conversion efficiency of 12.1%, so far the highest efficiency based on CH3NH3PbI3 with the planar heterojunction configuration. This method provides a simple approach to perovskite film preparation and paves the way for high reproducibility of films and devices. The underlying kinetic and thermodynamic parameters regarding the perovskite film growth are discussed as well.
2,136 citations
TL;DR: Two-dimensional hybrid perovskites are used as absorbers in solar cells and the 3D perovskite (MA)[PbI3] (2) has recently been identified as a promising absorber for solar cells, however, its instability to moisture requires anhydrous processing and operating conditions.
Abstract: Two-dimensional hybrid perovskites are used as absorbers in solar cells. Our first-generation devices containing (PEA)2(MA)2[Pb3I10] (1; PEA=C6H5(CH2)2NH3+, MA=CH3NH3+) show an open-circuit voltage of 1.18 V and a power conversion efficiency of 4.73 %. The layered structure allows for high-quality films to be deposited through spin coating and high-temperature annealing is not required for device fabrication. The 3D perovskite (MA)[PbI3] (2) has recently been identified as a promising absorber for solar cells. However, its instability to moisture requires anhydrous processing and operating conditions. Films of 1 are more moisture resistant than films of 2 and devices containing 1 can be fabricated under ambient humidity levels. The larger bandgap of the 2D structure is also suitable as the higher bandgap absorber in a dual-absorber tandem device. Compared to 2, the layered perovskite structure may offer greater tunability at the molecular level for material optimization.
1,725 citations
TL;DR: It is shown that cyclic stretching and releasing of thin MoS2 flakes with an odd number of atomic layers produces oscillating piezoelectric voltage and current outputs, whereas no output is observed for flakes with even number of layers, which may enable the development of applications in powering nanodevices, adaptive bioprobes and tunable/stretchable electronics/optoelectronics.
Abstract: The two-dimensional semiconducting material molybdenum disulphide shows strong piezoelectricity in its single-layered form, suggesting possible applications in nanoscale electromechanical devices for sensing and energy harvesting. Two-dimensional semiconducting materials are the focus of much research effort thanks to their unusual and potentially useful physical properties. Wenzhou Wu and colleagues now confirm theoretical expectations that one such material — molybdenum disulphide — exhibits strong piezoelectricity in its single-layered form. Such a coupling of mechanical and electrical properties suggests possible applications in nanoscale electromechanical devices for sensing and energy harvesting. The piezoelectric characteristics of nanowires, thin films and bulk crystals have been closely studied for potential applications in sensors, transducers, energy conversion and electronics1,2,3. With their high crystallinity and ability to withstand enormous strain4,5,6, two-dimensional materials are of great interest as high-performance piezoelectric materials. Monolayer MoS2 is predicted to be strongly piezoelectric, an effect that disappears in the bulk owing to the opposite orientations of adjacent atomic layers7,8. Here we report the first experimental study of the piezoelectric properties of two-dimensional MoS2 and show that cyclic stretching and releasing of thin MoS2 flakes with an odd number of atomic layers produces oscillating piezoelectric voltage and current outputs, whereas no output is observed for flakes with an even number of layers. A single monolayer flake strained by 0.53% generates a peak output of 15 mV and 20 pA, corresponding to a power density of 2 mW m−2 and a 5.08% mechanical-to-electrical energy conversion efficiency. In agreement with theoretical predictions, the output increases with decreasing thickness and reverses sign when the strain direction is rotated by 90°. Transport measurements show a strong piezotronic effect in single-layer MoS2, but not in bilayer and bulk MoS2. The coupling between piezoelectricity and semiconducting properties in two-dimensional nanomaterials may enable the development of applications in powering nanodevices, adaptive bioprobes and tunable/stretchable electronics/optoelectronics.
1,683 citations
TL;DR: A low-temperature processing technique is adopted to attain high-efficiency devices in both rigid and flexible substrates, using device structure substrate/ITO/PEDOT:PSS/CH(3)NH( 3)PbI(3-x)Cl(x)/PCBM/Al, where PEDOT?:PSS and PCBM are used as hole and electron transport layers, respectively.
Abstract: Perovskite compounds have attracted recently great attention in photovoltaic research. The devices are typically fabricated using condensed or mesoporous TiO2 as the electron transport layer and 2,2′7,7′-tetrakis-(N,N-dip-methoxyphenylamine)9,9′-spirobifluorene as the hole transport layer. However, the high-temperature processing (450 °C) requirement of the TiO2 layer could hinder the widespread adoption of the technology. In this report, we adopted a low-temperature processing technique to attain high-efficiency devices in both rigid and flexible substrates, using device structure substrate/ITO/PEDOT:PSS/CH3NH3PbI3–xClx/PCBM/Al, where PEDOT:PSS and PCBM are used as hole and electron transport layers, respectively. Mixed halide perovskite, CH3NH3PbI3–xClx, was used due to its long carrier lifetime and good electrical properties. All of these layers are solution-processed under 120 °C. Based on the proposed device structure, power conversion efficiency (PCE) of 11.5% is obtained in rigid substrates (glass/...
1,314 citations
TL;DR: The TENG can be a sensor that directly converts a mechanical triggering into a self-generated electric signal for detection of motion, vibration, mechanical stimuli, physical touching, and biological movement and is a new paradigm for energy harvesting.
Abstract: Triboelectrification is one of the most common effects in our daily life, but it is usually taken as a negative effect with very limited positive applications. Here, we invented a triboelectric nanogenerator (TENG) based on organic materials that is used to convert mechanical energy into electricity. The TENG is based on the conjunction of triboelectrification and electrostatic induction, and it utilizes the most common materials available in our daily life, such as papers, fabrics, PTFE, PDMS, Al, PVC etc. In this short review, we first introduce the four most fundamental modes of TENG, based on which a range of applications have been demonstrated. The area power density reaches 1200 W m−2, volume density reaches 490 kW m−3, and an energy conversion efficiency of ∼50–85% has been demonstrated. The TENG can be applied to harvest all kinds of mechanical energy that is available in our daily life, such as human motion, walking, vibration, mechanical triggering, rotation energy, wind, a moving automobile, flowing water, rain drops, tide and ocean waves. Therefore, it is a new paradigm for energy harvesting. Furthermore, TENG can be a sensor that directly converts a mechanical triggering into a self-generated electric signal for detection of motion, vibration, mechanical stimuli, physical touching, and biological movement. After a summary of TENG for micro-scale energy harvesting, mega-scale energy harvesting, and self-powered systems, we will present a set of questions that need to be discussed and explored for applications of the TENG. Lastly, since the energy conversion efficiencies for each mode can be different although the materials are the same, depending on the triggering conditions and design geometry. But one common factor that determines the performance of all the TENGs is the charge density on the two surfaces, the saturation value of which may independent of the triggering configurations of the TENG. Therefore, the triboelectric charge density or the relative charge density in reference to a standard material (such as polytetrafluoroethylene (PTFE)) can be taken as a measuring matrix for characterizing the performance of the material for the TENG.
1,169 citations
TL;DR: In this article, the authors observe slow transient effects causing hysteresis in the current-voltage characterization of hybrid organo-metal halide perovskites that can lead to an over- or underestimation of the solar cell device efficiency.
Abstract: Hybrid organo-metal halide perovskites are an exciting new class of solar absorber materials and have exhibited a rapid increase in solar cell efficiencies throughout the past two years to over 17% in both meso-structured and thin-film device architectures. We observe slow transient effects causing hysteresis in the current–voltage characterization of these devices that can lead to an over- or underestimation of the solar cell device efficiency. We find that the current–voltage (IV) measurement scan direction, measurement delay time, and light and voltage bias conditions prior to measurement can all have a significant impact upon the shape of the measured IV light curves and the apparent device efficiency. We observe that hysteresis-free light IV curves can be obtained at both extremely fast and slow voltage scan rates but only in the latter case are quasi-steady-state conditions achieved for a valid power conversion efficiency measurement. Hysteretic effects are also observed in devices utilizing alternative selective contacts but differ in magnitude and time scale, suggesting that the contact interfaces have a big effect on transients in perovskite-absorber devices. The transient processes giving rise to hysteresis are consistent with a polarization response of the perovskite absorber that results in changes in the photocurrent extraction efficiency of the device. The strong dependence of the hysteresis on light and voltage biasing conditions in thin film devices for a period of time prior to the measurement suggests that photo-induced ion migration may additionally play an important role in device hysteresis. Based on these observations, we provide recommendations for correct measurement and reporting of IV curves for perovskite solar cell devices.
1,121 citations
TL;DR: The demonstrated results of monolayer MoS2/Si-based solar cells hold the promise for integration of 2D materials with commercially available Si-based electronics in highly efficient devices.
Abstract: We realized photovoltaic operation in large-scale MoS2 monolayers by the formation of a type-II heterojunction with p-Si. The MoS2 monolayer introduces a built-in electric field near the interface between MoS2 and p-Si to help photogenerated carrier separation. Such a heterojunction photovoltaic device achieves a power conversion efficiency of 5.23%, which is the highest efficiency among all monolayer transition-metal dichalcogenide-based solar cells. The demonstrated results of monolayer MoS2/Si-based solar cells hold the promise for integration of 2D materials with commercially available Si-based electronics in highly efficient devices.
1,088 citations
TL;DR: In this paper, the authors reported the origin of the high efficiency in solution-processable bilayer solar cells based on methylammonium lead iodide (CH3NH3PbI3) and [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM).
Abstract: This work reports a study into the origin of the high efficiency in solution-processable bilayer solar cells based on methylammonium lead iodide (CH3NH3PbI3) and [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM). Our cell has a power conversion efficiency (PCE) of 5.2% under simulated AM 1.5G irradiation (100 mW cm−2) and an internal quantum efficiency of close to 100%, which means that nearly all the absorbed photons are converted to electrons and are efficiently collected at the electrodes. This implies that the exciton diffusion, charge transfer and charge collection are highly efficient. The high exciton diffusion efficiency is enabled by the long diffusion length of CH3NH3PbI3 relative to its thickness. Furthermore, the low exciton binding energy of CH3NH3PbI3 implies that exciton splitting at the CH3NH3PbI3/PC61BM interface is very efficient. With further increase in CH3NH3PbI3 thickness, a higher PCE of 7.4% could be obtained. This is the highest efficiency attained for low temperature solution-processable bilayer solar cells to date.
954 citations
TL;DR: This work presents an alternative approach to plasmonic metasurfaces by replacing the metallic resonators with high-refractive-index silicon cut-wires in combination with a silver ground plane, and demonstrates optical vortex beam generation using a meta-reflectarray with an azimuthally varied phase profile.
Abstract: Plasmonic metasurfaces have recently attracted much attention due to their ability to abruptly change the phase of light, allowing subwavelength optical elements for polarization and wavefront control. However, most previously demonstrated metasurface designs suffer from low coupling efficiency and are based on metallic resonators, leading to ohmic loss. Here, we present an alternative approach to plasmonic metasurfaces by replacing the metallic resonators with high-refractive-index silicon cut-wires in combination with a silver ground plane. We experimentally demonstrate that this meta-reflectarray can be used to realize linear polarization conversion with more than 98% conversion efficiency over a 200 nm bandwidth in the short-wavelength infrared band. We also demonstrate optical vortex beam generation using a meta-reflectarray with an azimuthally varied phase profile. The vortex beam generation is shown to have high efficiency over a wavelength range from 1500 to 1600 nm. The use of dielectric resonato...
TL;DR: A triple-junction tandem design is demonstrated by employing three distinct organic donor materials having bandgap energies ranging from 1.4 to 1.9 eV and can exhibit a record-high PCE of 11.5%.
Abstract: Tandem solar cells have the potential to improve photon conversion efficiencies (PCEs) beyond the limits of single-junction devices. In this study, a triple-junction tandem design is demonstrated by employing three distinct organic donor materials having bandgap energies ranging from 1.4 to 1.9 eV. Through optical modeling, balanced photon absorption rates are achieved and, thereby, the photo-currents are matched among the three subcells. Accordingly, an efficient triple-junction tandem organic solar cell can exhibit a record-high PCE of 11.5%.
TL;DR: This work demonstrates the application of an effective and cheap inorganic p-type hole-transporting material, copper thiocyanate, on lead halide perovskite-based devices and opens the door for integration of a class of abundant and inexpensive material for photovoltaic application.
Abstract: Organo-lead halide perovskites have attracted much attention for solar cell applications due to their unique optical and electrical properties With either low-temperature solution processing or vacuum evaporation, the overall conversion efficiencies of perovskite solar cells with organic hole-transporting material were quickly improved to over 15% during the last 2 years However, the organic hole-transporting materials used are normally quite expensive due to complicated synthetic procedure or high-purity requirement Here, we demonstrate the application of an effective and cheap inorganic p-type hole-transporting material, copper thiocyanate, on lead halide perovskite-based devices With low-temperature solution-process deposition method, a power conversion efficiency of 124% was achieved under full sun illumination This work represents a well-defined cell configuration with optimized perovskite morphology by two times of lead iodide deposition, and opens the door for integration of a class of abundant and inexpensive material for photovoltaic application
TL;DR: In this paper, a growth mode for via thermal annealing of the perovskite precursor film in a humid environment (e.g., ambient air) to greatly improve the film quality, grain size, carrier mobility, and lifetime was reported.
Abstract: Moisture is assumed to be detrimental to organometal trihalide perovskite, as excess water can damage the crystallinity of the perovskite structure. Here, we report a growth mode for via thermal annealing of the perovskite precursor film in a humid environment (e.g., ambient air) to greatly improve the film quality, grain size, carrier mobility, and lifetime. Our method produces devices with maximum power conversion efficiency of 17.1% and a fill factor of 80%, revealing a promising route to achieve high quality perovskite polycrystalline films with superior optoelectronic properties that can pave the way towards efficient photovoltaic conversion.
TL;DR: In this paper, an optomechanical system that converts microwaves to optical frequency light and vice versa is demonstrated, achieving a conversion efficiency of approximately 10% in terms of energy consumption.
Abstract: An optomechanical system that converts microwaves to optical frequency light and vice versa is demonstrated. The technique achieves a conversion efficiency of approximately 10%. The results indicate that the device could work at the quantum level, up- and down-converting individual photons, if it were cooled to millikelvin temperatures. It could, therefore, form an integral part of quantum-processor networks.
TL;DR: In this paper, the effects of the energy level between CH3NH3(= MA)PbI3 and MAPbBr3 and a series of triarylamine polymer derivatives containing fluorene and indenofluorene, which have different highest occupied molecular orbital (HOMO) levels, in terms of the photovoltaic behavior were investigated.
Abstract: Besides the generated photocurrent as a key factor that impacts the efficiency of solar cells, the produced photovoltage and fill factor are also of critical importance. Therefore, understanding and optimization of the open-circuit voltage (Voc) of perovskite solar cells, especially with an architecture consisting of mesoporous (mp)-TiO2/perovskite/hole transporting materials (HTMs), are required to further improve the conversion efficiency. In this work, we study the effects of the energy level between CH3NH3(= MA)PbI3 and MAPbBr3 and a series of triarylamine polymer derivatives containing fluorene and indenofluorene, which have different highest occupied molecular orbital (HOMO) levels, in terms of the photovoltaic behaviour. The voltage output of the device is found to be dependent on the higher energy level of perovskite solar absorbers as well as the HOMO level of the HTMs. The combination of MAPbBr3 and a deep-HOMO HTM leads to a high photovoltage of 1.40 V, with a fill factor of 79% and an energy conversion efficiency of up to 6.7%, which is the highest value reported to date for MAPbBr3 perovskite solar cells.
TL;DR: A small molecule named DR3TSBDT with dialkylthiol-substituted benzo[1,2-b:4,5-b']dithiophene (BDT) as the central unit was designed and synthesized for solution-processed bulk-heterojunction solar cells.
Abstract: A small molecule named DR3TSBDT with dialkylthiol-substituted benzo[1,2-b:4,5-b′]dithiophene (BDT) as the central unit was designed and synthesized for solution-processed bulk-heterojunction solar cells. A notable power conversion efficiency of 9.95% (certified 9.938%) has been achieved under AM 1.5G irradiation (100 mW cm–2), with an average PCE of 9.60% based on 50 devices.
TL;DR: These core/shell nanowires achieve the highest product of light absorption and charge separation efficiencies among BiVO4-based photoanodes to date and, even without an added catalyst, produce a photocurrent of 3.1 mA/cm under simulated sunlight and an incident photon-to-current conversion efficiency of ∼ 60% at 300-450 nm.
Abstract: We report a scalably synthesized WO3/BiVO4 core/shell nanowire photoanode in which BiVO4 is the primary light-absorber and WO3 acts as an electron conductor. These core/shell nanowires achieve the highest product of light absorption and charge separation efficiencies among BiVO4-based photoanodes to date and, even without an added catalyst, produce a photocurrent of 3.1 mA/cm(2) under simulated sunlight and an incident photon-to-current conversion efficiency of ∼ 60% at 300-450 nm, both at a potential of 1.23 V versus RHE.
TL;DR: In this article, two easy-accessible solution-processed, environmentally friendly organic small-molecule cathode interlayers, with perylene diimides (PDI) as the core and amino (PDIN) or amino N-oxide (PDINO), as the terminal substituent, are explored.
Abstract: With the power conversion efficiency of polymer solar cells (PSCs) approaching the milestone value of 10%, their instability associated with a low work function metal cathode, particularly in the presence of oxygen and moisture, becomes a critical issue for real applications. To alleviate the air-sensitive problem, two easy-accessible solution-processed, environmentally friendly organic small-molecule cathode interlayers, with perylene diimides (PDI) as the core and amino (PDIN) or amino N-oxide (PDINO) as the terminal substituent, are explored. Benefitting from the extended planar structure of the PDI units, the two interlayer materials show high conductivities of ∼10−5 S cm−1, which make them capable of functioning efficiently in a wide thickness range of 6 to 25 nm. This is the first time that thickness-insensitive small-molecule-based cathode interlayers are reported. It is also found that the work function tuning effect of the two PDI-based interlayers allows high work function metals (such as Au and Ag) to act as the cathode. With the conventional device structure with PTB7 as a donor and PC70BM as an acceptor, the PDINO-based devices exhibit an efficiency of 8.24% with Al as the top electrode and 8.16% with Ag as the top electrode, much higher than that of the corresponding Ca/Al-based device (6.98%). The high efficiency of 8.35% is also achieved in the device with PTB7-Th as the donor. The success of the two PDI-interlayers indicates that π-delocalized planar structures with high electron affinities could be particularly useful in developing high-performance organic interlayer materials.
TL;DR: In this paper, a planar perovskite-PCBM solar cell with CH3NH3PbI3 film and a thin PCBM film is fabricated by the solution-process at low temperature.
Abstract: Highly efficient p–i–n perovskite solar cells employing a flat and thick CH3NH3PbI3 film and a thin PCBM film are fabricated by the solution-process at low temperature. Through attainment of optimized PCBM thickness and insertion of the LiF interlayer, the unit cell shows 14.1% of overall power conversion efficiency (PCE) with a Jsc of 20.7 mA cm−2, a Voc of 0.866 V, and a FF of 78.3% under AM 1.5G 100 mW cm−2 conditions, while a larger area 10 cell serially connected module (10 × 10 cm2) shows an 8.7% PCE. These PCE values are the highest reported to date for the planar perovskite–PCBM solar cells.
TL;DR: In this paper, a series of semi-crystalline, low band gap (LBG) polymers and demonstrate the fabrication of highly efficient polymer solar cells (PSCs) in a thick single-cell architecture.
Abstract: We report a series of semi-crystalline, low band gap (LBG) polymers and demonstrate the fabrication of highly efficient polymer solar cells (PSCs) in a thick single-cell architecture. The devices achieve a power conversion efficiency (PCE) of over 7% without any post-treatment (annealing, solvent additive, etc.) and outstanding long-term thermal stability for 200 h at 130 °C. These excellent characteristics are closely related to the molecular structures where intra- and/or intermolecular noncovalent hydrogen bonds and dipole–dipole interactions assure strong interchain interactions without losing solution processability. The semi-crystalline polymers form a well-distributed nano-fibrillar networked morphology with PC70BM with balanced hole and electron mobilities (a h/e mobility ratio of 1–2) and tight interchain packing (a π–π stacking distance of 3.57–3.59 A) in the blend films. Furthermore, the device optimization with a processing additive and methanol treatment improves efficiencies up to 9.39% in a ∼300 nm thick conventional single-cell device structure. The thick active layer in the PPDT2FBT:PC70BM device attenuates incident light almost completely without damage in the fill factor (0.71–0.73), showing a high short-circuit current density of 15.7–16.3 mA cm−2. Notably, PPDT2FBT showed negligible changes in the carrier mobility even at ∼1 μm film thickness.
TL;DR: In this article, the use of two, rather than one, donor polymers in an organic solar cell was shown to enhance charge separation, transport and recombination, and two-layer solar cells were used.
Abstract: The use of two, rather than one, donor polymers in an organic solar cell is shown to enhance charge separation, transport and recombination.
TL;DR: In this paper, the authors present a list of the highest independently confirmed efficiencies for solar cells and modules and provide guidelines for inclusion of results into these tables and new entries since January 2010 are reviewed.
Abstract: Consolidated tables showing an extensive listing of the highest independently confirmed efficiencies for solar cells and modules are presented. Guidelines for inclusion of results into these tables are outlined and new entries since January 2010 are reviewed. Copyright # 2010 John Wiley & Sons, Ltd.
TL;DR: A simple three-layer architecture comprising two non-fullerene acceptors and a donor, in which an energy-relay cascade enables an efficient two-step exciton dissociation process, confirms that multilayer cascade structures are a promising alternative to conventional donor- fullerene organic solar cells.
Abstract: In order to increase the power conversion efficiency of organic solar cells, their absorption spectrum should be broadened while maintaining efficient exciton harvesting. This requires the use of multiple complementary absorbers, usually incorporated in tandem cells or in cascaded exciton-dissociating heterojunctions. Here we present a simple three-layer architecture comprising two non-fullerene acceptors and a donor, in which an energy-relay cascade enables an efficient two-step exciton dissociation process. Excitons generated in
TL;DR: It is demonstrated that, using Cs2SnI6 as a hole transporter, it can successfully fabricate in air a solid-state dye-sensitized solar cell (DSSC) with a mesoporous TiO2 film and a more efficient mixture of porphyrin dyes has been achieved.
Abstract: We introduce a new class of molecular iodosalt compounds for application in next-generation solar cells. Unlike tin-based perovskite compounds CsSnI3 and CH3NH3SnI3, which have Sn in the 2+ oxidation state and must be handled in an inert atmosphere when fabricating solar cells, the Sn in the molecular iodosalt compounds is in the 4+ oxidation state, making them stable in air and moisture. As an example, we demonstrate that, using Cs2SnI6 as a hole transporter, we can successfully fabricate in air a solid-state dye-sensitized solar cell (DSSC) with a mesoporous TiO2 film. Doping Cs2SnI6 with additives helps to reduce the internal device resistance, improving cell efficiency. In this way, a Z907 DSSC delivers 4.7% of energy conversion efficiency. By using a more efficient mixture of porphyrin dyes, an efficiency near 8% with photon confinement has been achieved. This represents a significant step toward the realization of low-cost, stable, lead-free, and environmentally benign next-generation solid-state so...
TL;DR: A sandwich-structured CdS-Au-TiO2 nanorod array as the photoanode in a photoelectrochemical cell (PEC) for hydrogen generation via splitting water shows defect states cannot be ignored when designing QD-sensitized solar cells and has implications for the design of efficient solar-energy-harvesting devices.
Abstract: This paper presents a sandwich-structured CdS-Au-TiO2 nanorod array as the photoanode in a photoelectrochemical cell (PEC) for hydrogen generation via splitting water. The gold nanoparticles sandwiched between the TiO2 nanorod and the CdS quantum dot (QD) layer play a dual role in enhancing the solar-to-chemical energy conversion efficiency. First, the Au nanoparticles serve as an electron relay, which facilitates the charge transfer between CdS and TiO2 when the CdS QDs are photoexcited by wavelengths shorter than 525 nm. Second, the Au nanoparticles act as a plasmonic photosensitizer, which enables the solar-to-hydrogen conversion at wavelengths longer than the band edge of CdS, extending the photoconversion wavelength from 525 to 725 nm. The dual role of Au leads to a photocurrent of 4.07 mA/cm2 at 0 V (vs Ag|AgCl) under full solar spectrum irradiation and a maximum solar-to-chemical energy conversion efficiency of 2.8%. An inversion analysis is applied to the transient absorption spectroscopy data, tr...
TL;DR: In this paper, a gas-assisted solution processing technique has been used to change the kinetics of nucleation and crystal growth of the perovskite during spin coating, producing very uniform thin films consisting of densely packed single crystalline grains.
TL;DR: A power conversion efficiency of 10.4% is demonstrated in planar CH3 NH3 PbBr3 hybrid solar cells without hysteresis of the J-V curve, by way of controlled crystallization in the spin-coating process.
Abstract: A power conversion efficiency of 10.4% is demonstrated in planar CH3 NH3 PbBr3 hybrid solar cells without hysteresis of the J-V curve, by way of controlled crystallization in the spin-coating process. The high efficiency is attributed to the formation of a dense CH3 NH3 PbBr3 thin film by the introduction of HBr solution because the HBr increases the solubility of the CH3 NH3 PbBr3 and forms a thinner CH3 NH3 PbBr3 layer with full surface coverage.
TL;DR: Guo et al. as discussed by the authors reviewed light trapping with metallic nanostructures for thin film solar cells and selective solar absorbers, and showed that the presence of metallic nanoparticles in a solar cell or a solar absorber can aid light absorption by inducing strong, local fieldenhancement effects or coupling to resonant plasmon modes.
Abstract: Solar energy is abundant and environmentally friendly. Light trapping in solar-energy-harvesting devices or structures is of critical importance. This article reviews light trapping with metallic nanostructures for thin film solar cells and selective solar absorbers. The metallic nanostructures can either be used in reducing material thickness and device cost or in improving light absorbance and thereby improving conversion efficiency. The metallic nanostructures can contribute to light trapping by scattering and increasing the path length of light, by generating strong electromagnetic field in the active layer, or by multiple reflections/absorptions. We have also discussed the adverse effect of metallic nanostructures and how to solve these problems and take full advantage of the light-trapping effect. In recent years, researchers have demonstrated a number of new schemes for enhancing the absorption of light in solar cells. Chuan Fei Guo and colleagues from the University of Houston in the USA and National Center for Nanoscience and Technology of China in Beijing have now reviewed the use of metallic nanostructures for trapping light in photovoltaic devices. In particular, the presence of metallic nanoparticles in a solar cell or a solar absorber can aid light absorption by inducing strong, local field-enhancement effects or coupling to resonant plasmon modes. Such particles can also promote scattering and thus increase path lengths for light within the device. Solar cells that utilize this approach are either more efficient or substantially thinner than those that do not, thus reducing material costs and creating the opportunity for ultrathin, flexible devices.