Showing papers by "Jun Hong Noh published in 2015"

High-performance photovoltaic perovskite layers fabricated through intramolecular exchange

Abstract: The band gap of formamidinium lead iodide (FAPbI3) perovskites allows broader absorption of the solar spectrum relative to conventional methylammonium lead iodide (MAPbI3). Because the optoelectronic properties of perovskite films are closely related to film quality, deposition of dense and uniform films is crucial for fabricating high-performance perovskite solar cells (PSCs). We report an approach for depositing high-quality FAPbI3 films, involving FAPbI3 crystallization by the direct intramolecular exchange of dimethylsulfoxide (DMSO) molecules intercalated in PbI2 with formamidinium iodide. This process produces FAPbI3 films with (111)-preferred crystallographic orientation, large-grained dense microstructures, and flat surfaces without residual PbI2. Using films prepared by this technique, we fabricated FAPbI3-based PSCs with maximum power conversion efficiency greater than 20%.

Compositional engineering of perovskite materials for high-performance solar cells

Abstract: Inorganic–organic lead halide perovskite could be efficient when used as the light-harvesting component of solar cells; here incorporation of methylammonium lead bromide into formamidinium lead iodide stabilizes the perovskite and improves the power conversion efficiency of the solar cell up to 17.9 per cent. Inorganic–organic lead halide perovskites are currently attracting considerable interest for solar-cell applications. Most of the best performing perovskite solar cells to date have made use of methylammonium-based perovskites; formamidinium-based perovskites have also shown promise, but are not as stable. Now Nam Joong Jeon and colleagues show that the formamidinium-based perovskites can be stabilized by the addition of some methylammonium-based perovskite, and that solar cells incorporating the resulting compositionally tuned materials can reach new heights of efficiency. Of the many materials and methodologies aimed at producing low-cost, efficient photovoltaic cells, inorganic–organic lead halide perovskite materials1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17 appear particularly promising for next-generation solar devices owing to their high power conversion efficiency. The highest efficiencies reported for perovskite solar cells so far have been obtained mainly with methylammonium lead halide materials1,2,3,4,5,6,7,8,9,10. Here we combine the promising—owing to its comparatively narrow bandgap—but relatively unstable formamidinium lead iodide (FAPbI3) with methylammonium lead bromide (MAPbBr3) as the light-harvesting unit in a bilayer solar-cell architecture13. We investigated phase stability, morphology of the perovskite layer, hysteresis in current–voltage characteristics, and overall performance as a function of chemical composition. Our results show that incorporation of MAPbBr3 into FAPbI3 stabilizes the perovskite phase of FAPbI3 and improves the power conversion efficiency of the solar cell to more than 18 per cent under a standard illumination of 100 milliwatts per square centimetre. These findings further emphasize the versatility and performance potential of inorganic–organic lead halide perovskite materials for photovoltaic applications.

Efficient CH3NH3PbI3 Perovskite Solar Cells Employing Nanostructured p-Type NiO Electrode Formed by a Pulsed Laser Deposition

Abstract: Highly transparent and nanostructured nickel oxide (NiO) films through pulsed laser deposition are introduced for efficient CH3 NH3 PbI3 perovskite solar cells. The (111)-oriented nanostructured NiO film plays a key role in extracting holes and preventing electron leakage as hole transporting material. The champion device exhibits a power conversion efficiency of 17.3% with a very high fill factor of 0.813.

High-performance flexible perovskite solar cells exploiting Zn2SnO4 prepared in solution below 100 °C.

Abstract: There has been impressive progress in the development of perovskite solar cells in recent years, but the best performing systems tend to be fabricated on glass surfaces. Here, the authors present a cell built on a polymer substrate, allowing flexibility whilst maintaining high efficiency.

Fabrication of metal-oxide-free CH3NH3PbI3 perovskite solar cells processed at low temperature

Abstract: Efficient metal-oxide-free perovskite solar cells were successfully developed by employing the N–I–P architecture. The modified solvent engineering process employing a diethylether drip as an orthogonal solvent enabled fabrication of a multi-layered device comprising FTO/PEI/PCBM/MAPbI3/PTAA/Au at low temperature (≤100 °C). Optimization of the thickness of the phenyl-C61-butyric acid methyl ester (PCBM) layer in the planar device yielded an overall power conversion efficiency (PCE) of 15.3% with a large hysteresis but a steady-state efficiency of 13.9% under AM 1.5G 100 mW cm−2 illumination. The use of the low-temperature processed dense-TiO2 layer in conjunction with the PCBM layer gave rise to performance comparable to that of the single electron transport layer (ETL) device and enabled fabrication of an efficient, flexible perovskite solar cell with a PCE of 11.1%.

Steps toward efficient inorganic–organic hybrid perovskite solar cells

Abstract: Crystalline silicon dominates the solar panel industry today but remains relatively expensive to manufacture. If devices could be fabricated from inexpensive materials by a simple solution process without the need for high-temperature annealing, their cost could be considerably reduced. Recently, inorganic–organic (I/O) hybrid systems based on inorganic nanoparticles (including quantum dots) and perovskite materials as light harvesters with organic hole-conducting materials have shown great potential for efficient solar cells due to the combination of superior optical properties and solution-based processes. In this review, we describe the relevant morphological factors and the performance of perovskite solar cells with tuned heterojunctions. In particular, we describe the mediator retarding the rapid crystallization of perovskite layers for a bilayer configuration. Appropriate processes and chemical engineering induced the formation of well-crystallized perovskite materials with extremely uniform and dense perovskite layers and remarkably improved the performance of the cells with a National Renewable Energy Laboratory (NREL)-certified record efficiency of 20.1%.

Method for preparing inorganic/organic hybrid perovskite compound film

Abstract: The present invention relates to a method for preparing an inorganic/organic hybrid perovskite compound film, and a structure for a solar cell and, specifically, a method for preparing an inorganic/organic hybrid perovskite compound film, according to one embodiment of the present invention, can comprise the steps of: a) forming, on a substrate layer, an adduct layer containing an adduct of halogenated metal and guest molecule; and b) preparing an inorganic/organic hybrid perovskite compound film by reacting the adduct layer and an organic halide.

Synthesis of carbon-incorporated titanium oxide nanocrystals by pulsed solution plasma: electrical, optical investigation and nanocrystals analysis

Abstract: TiOx/carbon composite nanosheets were synthesized by a “pulsed solution plasma” technique in a Ti-contained solution. The discharge characteristics of the plasma were investigated via the resistance of the plasma channel from current and voltage profiles as a function of capacitor energy. Furthermore, the Ti-based oxides were characterized in detail using high-resolution transmission electron microscopy and selected area electron diffraction. Finally, the formation mechanism of the product was discussed through optical emission spectroscopy. The analyses revealed that the products were composed of spherical nanoparticles of TiO, TiO2 rutile phases and polycrystalline anatase TiO2/carbon composite nanosheets, which were formed by plasma or plasma-induced reactions between species in Ti-contained solution.