Showing papers on "Perovskite solar cell published in 2021"

Interfacial toughening with self-assembled monolayers enhances perovskite solar cell reliability

Abstract: Iodine-terminated self-assembled monolayer (I-SAM) was used in perovskite solar cells (PSCs) to achieve a 50% increase of adhesion toughness at the interface between the electron transport layer (ETL) and the halide perovskite thin film to enhance mechanical reliability. Treatment with I-SAM also increased the power conversion efficiency from 20.2% to 21.4%, reduced hysteresis, and improved operational stability with a projected T80 (time to 80% initial efficiency retained) increasing from ~700 hours to 4000 hours under 1-sun illumination and with continuous maximum power point tracking. Operational stability-tested PSC without SAMs revealed extensive irreversible morphological degradation at the ETL/perovskite interface, including voids formation and delamination, whereas PSCs with I-SAM exhibited minimal damage accumulation. This difference was attributed to a combination of a decrease in hydroxyl groups at the interface and the higher interfacial toughness.

High-Efficiency Perovskite Solar Cells with Imidazolium-Based Ionic Liquid for Surface Passivation and Charge Transport.

Abstract: Surface defects have been a key constraint for perovskite photovoltaics. Herein, 1,3-dimethyl-3-imidazolium hexafluorophosphate (DMIMPF6 ) ionic liquid (IL) is adopted to passivate the surface of a formamidinium-cesium lead iodide perovskite (Cs0.08 FA0.92 PbI3 ) and also reduce the energy barrier between the perovskite and hole transport layer. Theoretical simulations and experimental results demonstrate that Pb-cluster and Pb-I antisite defects can be effectively passivated by [DMIM]+ bonding with the Pb2+ ion on the perovskite surface, leading to significantly suppressed non-radiative recombination. As a result, the solar cell efficiency was increased to 23.25 % from 21.09 %. Meanwhile, the DMIMPF6 -treated perovskite device demonstrated long-term stability because the hydrophobic DMIMPF6 layer blocked moisture permeation.

Stable and low-photovoltage-loss perovskite solar cells by multifunctional passivation

Abstract: Metal halide perovskite solar cells have demonstrated a high power conversion efficiency (PCE), and further enhancement of the PCE requires a reduction of the bandgap-voltage offset (WOC) and the non-radiative recombination photovoltage loss (ΔVOC,nr). Here, we report an effective approach for reducing the photovoltage loss through the simultaneous passivation of internal bulk defects and dimensionally graded two-dimensional perovskite interface defects. Through this dimensionally graded perovskite formation approach, an open-circuit voltage (VOC) of 1.24 V was obtained with a champion PCE of 21.54% in a 1.63 eV perovskite system (maximum VOC = 1.25 V, WOC = 0.38 V and ΔVOC,nr = 0.10 V); we further decreased the WOC to 0.326 V in a 1.53 eV perovskite system with a VOC of 1.21 V and a PCE of 23.78% (certified 23.09%). This approach is equally effective in achieving a low WOC (ΔVOC,nr) in 1.56 eV and 1.73 eV perovskite solar cell systems, and further leads to the substantially improved operational stability of perovskite solar cells. The use of a dimensionally graded 2D perovskite interface and passivation results in perovskite solar cells with very low photovoltage loss.

Interpenetrating interfaces for efficient perovskite solar cells with high operational stability and mechanical robustness.

Abstract: The perovskite solar cell has emerged rapidly in the field of photovoltaics as it combines the merits of low cost, high efficiency, and excellent mechanical flexibility for versatile applications However, there are significant concerns regarding its operational stability and mechanical robustness Most of the previously reported approaches to address these concerns entail separate engineering of perovskite and charge-transporting layers Herein we present a holistic design of perovskite and charge-transporting layers by synthesizing an interpenetrating perovskite/electron-transporting-layer interface This interface is reaction-formed between a tin dioxide layer containing excess organic halide and a perovskite layer containing excess lead halide Perovskite solar cells with such interfaces deliver efficiencies up to 222% and 201% for rigid and flexible versions, respectively Long-term (1000 h) operational stability is demonstrated and the flexible devices show high endurance against mechanical-bending (2500 cycles) fatigue Mechanistic insights into the relationship between the interpenetrating interface structure and performance enhancement are provided based on comprehensive, advanced, microscopic characterizations This study highlights interface integrity as an important factor for designing efficient, operationally-stable, and mechanically-robust solar cells Operational stability and mechanical robustness remain as engineering bottlenecks in perovskite solar cells technology Here, Dong et al introduce an interpenetrating perovskite at the electron-transporting-layer interface that enables a 1000-hour stable operation and high endurance against bending fatigue over 2500 cycles

Illumination Durability and High-Efficiency Sn-Based Perovskite Solar Cell under Coordinated Control of Phenylhydrazine and Halogen Ions

Abstract: Summary The organic-inorganic hybrid Sn-based perovskite has attracted extensive attention because of its more suitable band gap and environmentally friendly characteristics, but the natural oxidization of Sn2+ makes for unsatisfactory illumination stability and efficiency in solar cells. Here, we successfully proved that the synergistical introduction of phenylhydrazine cation (PhNHNH3+) and halogen anions (Cl– and Br–) could substantially improve the illumination stability of FASnI3 (FA stands for NH2CH = NH2+) through the combination of experiments and theoretical calculations. The resultant device achieved a power conversion efficiency of 13.4% (certified 12.4%) with striking long-term durability; i.e., the optimized device maintained 82% of the original efficiency over 330 h under AM1.5G one-sun illumination. This method provides a universal way for improving the illumination stability and efficiency of Sn-based perovskites.

The critical role of composition-dependent intragrain planar defects in the performance of MA1–xFAxPbI3 perovskite solar cells

Abstract: Perovskite solar cells show excellent power conversion efficiencies, long carrier diffusion lengths and low recombination rates. This encourages a view that intragrain defects are electronically benign with little impact on device performance. In this study we varied the methylammonium (MA)/formamidinium (FA) composition in MA1–xFAxPbI3 (x = 0–1), and compared the structure and density of the intragrain planar defects with device performance, otherwise keeping the device nominally the same. We found that charge carrier lifetime, open-circuit voltage deficit and current density–voltage hysteresis correlate empirically with the density and structure of {111}c planar defects (x = 0.5–1) and {112}t twin boundaries (x = 0–0.1). The best performance parameters were found when essentially no intragrain planar defects were evident (x = 0.2). Similarly, reducing the density of {111}c planar defects through MASCN vapour treatment of FAPbI3 (x ≈ 1) also improved performance. These observations suggest that intragrain defect control can provide an important route for improving perovskite solar cell performance, in addition to well-established parameters such as grain boundaries and interfaces. The role of intragrain planar defects in halide perovskite solar cell devices remains elusive. Now, Li et al. tune the composition of the perovskite layer to minimize the planar defect density and observe an improvement in the device performance.

Tailored Lattice "Tape" to Confine Tensile Interface for 11.08%-Efficiency All-Inorganic CsPbBr3 Perovskite Solar Cell with an Ultrahigh Voltage of 1.702 V.

Abstract: The crystal distortion such as lattice strain and defect located at the surfaces and grain boundaries induced by soft perovskite lattice highly determines the charge extraction-transfer dynamics and recombination to cause an inferior efficiency of perovskite solar cells (PSCs). Herein, the authors propose a strategy to significantly reduce the superficial lattice tensile strain by means of incorporating an inorganic 2D Cl-terminated Ti3 C2 (Ti3 C2 Clx ) MXene into the bulk and surface of CsPbBr3 film. Arising from the strong interaction between Cl atoms in Ti3 C2 Clx and the under-coordinated Pb2+ in CsPbBr3 lattice, the expanded perovskite lattice is compressed and confined to act as a lattice "tape", in which the PbCl bond plays a role of "glue" and the 2D Ti3 C2 immobilizes the lattice. Finally, the defective surface is healed and a champion efficiency as high as 11.08% with an ultrahigh open-circuit voltage up to 1.702 V is achieved on the best all-inorganic CsPbBr3 PSC, which is so far the highest efficiency record for this kind of PSCs. Furthermore, the unencapsulated device demonstrates nearly unchanged performance under 80% relative humidity over 100 days and 85 °C over 30 days.

Localized Electron Density Engineering for Stabilized B-γ CsSnI3-Based Perovskite Solar Cells with Efficiencies >10%

Abstract: Black orthorhombic (B-γ) CsSnI3 with low toxicity and excellent optoelectronic properties is a promising candidate for perovskite solar cell (PSC). However, the performance of the B-γ CsSnI3-based ...

Moisture-Resistant FAPbI3 Perovskite Solar Cell with 22.25 % Power Conversion Efficiency through Pentafluorobenzyl Phosphonic Acid Passivation

Abstract: Perovskite solar cells (PSCs) are displaying auspicious candidacy towards photovoltaic technology based on their features including low-cost assembling, exceptional performance, and low-temperature solution processing. However, the progression of PSCs in the direction of commercialized upgrade desires high efficiency and long-term stability. The surface and grain boundaries of perovskite layer, as well as interfaces are critical factors intended for the performance of the assembled cells. The defects mainly located in the perovskite surfaces can trigger the hysteresis, carrier recombination, and degradation, which obstacle the progress in the power conversion efficiency (PCE) of the ensuing cells. Herein, we propose to stabilize the α-FAPbI 3 perovskite phase without scarifying the spectral features by taking the benefits of 2,3,4,5,6-pentafluorobenzyl phosphonic acid (PFBPA) molecule as a passivation agent for the first time. Accordingly, high-quality PSCs with improved efficiency of 22.25% was attained with respectable cell parameters compared to the pristine cells without passivation layer. Remarkably, the PFBPA passivated ultrathin layer effectually prevents the perovskite layer from moisture, resulting in better long-term stability for unsealed PSCs maintain >90% of the original efficiency under different humidity levels (40 to 75%) after 600 h. This work finds out that the PFBPA passivation has a considerable impact in obtaining high-quality and stable FAPbI 3 films for extra beneficent both the efficiency and stability of PSCs.

Understanding the perovskite/self-assembled selective contact interface for ultra-stable and highly efficient p–i–n perovskite solar cells

Abstract: Current perovskite solar cell efficiency is close to silicon's record values. Yet, the roadblock for industrialization of this technology is its stability. The stability of the solar cell not only depends on the stability of the perovskite material itself but also notably on its contact layers and their interface with the perovskite, which plays a paramount role. This study rationalizes the design of new molecules to form self-assembled monolayers as a hole-selective contact. The new molecules increased the stability of the perovskite solar cells to maintain 80% of their initial PCE of 21% for 250 h at 85 °C under 1 sun illumination. The excellent charge collection properties as well as perovskite passivation effect enable the highly stable and efficient devices to demonstrate the vast potential of this new type of contact in photovoltaic application.

Automatic light-adjusting electrochromic device powered by perovskite solar cell

Abstract: Electrochromic devices can modulate their light absorption under a small driving voltage, but the requirement for external electrical supplies causes response-lag To address this problem, self-powered electrochromic devices have been studied recently However, insensitivity to the surrounding light and unsatisfactory stability of electrochromic devices have hindered their critical applications Herein, novel perovskite solar cell-powered all-in-one gel electrochromic devices have been assembled and studied in order to achieve automatic light adjustment Two alkynyl-containing viologen derivatives are synthesized as electrochromic materials, the devices with very high stability (up to 70000 cycles) serves as the energy storage and smart window, while the perovskite solar cell with power-conversion-efficiency up to 183% serves as the light detector and power harvester The combined devices can automatically switch between bleached and colored state to adjust light absorption with variable surrounding light intensity in real-time swiftly, which establish significant potentials for applications as modern all-day intelligent windows

Device simulation of highly efficient eco-friendly CH3NH3SnI3 perovskite solar cell.

Abstract: Photoexcited lead-free perovskite CH3NH3SnI3 based solar cell device was simulated using a solar cell capacitance simulator. It was modeled to investigate its output characteristics under AM 1.5G illumination. Simulation efforts are focused on the thickness, acceptor concentration and defect density of absorber layer on photovoltaic properties of solar cell device. In addition, the impact of various metal contact work function was also investigated. The simulation results indicate that an absorber thickness of 500 nm is appropriate for a good photovoltaic cell. Oxidation of Sn2+ into Sn4+ was considered and it is found that the reduction of acceptor concentration of absorber layer significantly improves the device performance. Further, optimizing the defect density (1014 cm−3) of the perovskite absorber layer, encouraging results of the Jsc of 40.14 mA/cm2, Voc of 0.93 V, FF of 75.78% and PCE of 28.39% were achieved. Finally, an anode material with a high work function is necessary to get the device's better performance. The high-power conversion efficiency opens a new avenue for attaining clean energy.

Spacer Engineering Using Aromatic Formamidinium in 2D/3D Hybrid Perovskites for Highly Efficient Solar Cells

Abstract: Organic spacers play an important role in 2D/3D hybrid perovskites, which could combine the advantages of high stability of 2D perovskites and high efficiency of 3D perovskites. Here, a class of aromatic formamidiniums (ArFA) was developed as spacers for 2D/3D perovskites. It is found that the bulky aromatic spacer ArFA in 2D/3D perovskites could induce better crystalline growth and orientation, reduce the defect states, and enlarge spatially resolved carrier lifetime thanks to the multiple NH···I hydrogen-bonding interactions between ArFA and inorganic [PbI6]4- layers. As a result, compared to the control device with efficiency of 19.02%, the 2D/3D perovskite device based on such an optimized organic salt, namely benzamidine hydrochloride (PhFACl), exhibits a dramatically improved efficiency of 22.39% along with improved long-term thermal stability under 80 °C over 1400 h. Importantly, a champion efficiency of 23.36% was further demonstrated through device engineering for PhFACl-based 2D/3D perovskite solar cells. These results indicate the great potential of this class of ArFA spacers in highly efficient 2D/3D perovskite solar cells.

In situ growth of ultra-thin perovskitoid layer to stabilize and passivate MAPbI3 for efficient and stable photovoltaics

Abstract: The efficiency and stability of typical three-dimensional (3D) MAPbI3 perovskite-based solar cells are highly restricted, due to the weak interaction between methylammonium (MA+) and [PbI6]4-octahedra in the 3D structure, which can cause the ion migration and the related defects. Here, we found that the in situ-grown perovskitoid TEAPbI3 layer on 3D MAPbI3 can inhibit the MA+ migration in a polar solvent, thus enhancing the thermal and moisture stability of perovskite films. The crystal structure and orientation of TEAPbI3 are reported for the first time by single crystal and synchrotron radiation analysis. The ultra-thin perovskitoid layer can reduce the trap states and accelerate photo-carrier diffusion in perovskite solar cells, as confirmed by ultra-fast spectroscopy. The power conversion efficiency of TEAPbI3-MAPbI3 based solar cells increases from 18.87% to 21.79% with enhanced stability. This work suggests that passivation and stabilization by in situ-grown perovskitoid can be a promising strategy for efficient and stable perovskite solar cells.

Organic Tetrabutylammonium Cation Intercalation to Heal Inorganic CsPbI3 Perovskite

Abstract: The in-situ formation of reduced dimensional perovskite layer via post-synthesis ion exchange has been an effective way of passivating organic-inorganic hybrid perovskites. In contrast, cesium ions in Cs based inorganic perovskite with strong ionic binding energy cannot exchange with those well-known organic cations to form reduced dimensional perovskite. Herein, we demonstrate that tetrabutylammonium (TBA + ) cation can intercalate into CsPbI 3 to effectively substitute the Cs cation to form one-dimensional (1D) TBAPbI 3 layer in the post-synthesis TBAI treatment. Such TBA cation intercalation leads to in-situ formation of TBAPbI 3 protective layer to heal defects at surface of inorganic CsPbI 3 perovskite. The TBAPbI 3 -CsPbI 3 perovskite exhibited enhanced stability and lower defect density, and the corresponding perovskite solar cell devices achieved an improved efficiency up to 18.32% compared to the control one's efficiency of 15.85%. Our findings would inspire further investigation and development of reduced dimensional perovskite protection strategy for inorganic perovskites.

Evidence of improved power conversion efficiency in lead-free CsGeI3 based perovskite solar cell heterostructure via scaps simulation

Abstract: Simulation has been performed on fully lead-free inorganic cesium germanium tri-iodide (CsGeI3) perovskite solar cell heterostructure and achieved a champion power conversion efficiency (PCE) of ∼18.30% with significantly improved device parameters. The influence of thickness of an electron transport layer, a hole transport layer, an absorber, defect density, doping concentration, electron affinity, temperature, and series resistance issued for the optimization of the lead-free device is studied. It is confirmed via the scaps simulation results that this device is perfectly optimized with the experimental results and demonstrates the maximum possible improved power conversion efficiency in a fully inorganic lead-free CsGeI3 perovskite solar cell device. The final optimized device performance parameters are as follows: %PCE = 18.30%, %FF = 75.46%, Jsc = 23.31 mA/cm2, and Voc = 1.04 V. In the future, this efficiency may offer prominent potential as a substitute in a highly efficient green solar absorber material for photovoltaic applications after confirmation in the laboratory.

Low-Cost Dopant Additive-Free Hole-Transporting Material for a Robust Perovskite Solar Cell with Efficiency Exceeding 21%

Abstract: Developing hole-transporting materials (HTMs) with appropriate molecular configuration and charge mobility is important to improve perovskite solar cell (PSC) photovoltaic performance and their fea...

Crystallization Kinetics Modulation of FASnI3 Films with Pre-nucleation Clusters for Efficient Lead-Free Perovskite Solar Cells.

Abstract: Tin halide perovskites are rising as promising materials for lead-free perovskite solar cells (PSCs). However, the crystallization rate of tin halide perovskites is much faster than the lead-based analogs, leading to more rampant trap states and lower efficiency. Here, we disclose a key finding to modulate the crystallization kinetics of FASnI3 through a non-classical nucleation mechanism based on pre-nucleation clusters (PNCs). By introducing piperazine dihydriodide to tune the colloidal chemistry of the FASnI3 perovskite precursor solution, stable clusters could be readily formed in the solution before nucleation. These pre-nucleation clusters act as intermediate phase and thus can reduce the energy barrier for the perovskite nucleation, resulting in a high-quality perovskite film with lower defect density. This PNCs-based method has led to a conspicuous photovoltaic performance improvement for FASnI3 -based PSCs, delivering an impressive efficiency of 11.39 % plus improved stability.