Proceedings of International Conference on Hybrid and Organic Photovoltaics (HOPV16)
Publication date: 28th March 2016
Organo-lead halide perovskite solar cells can be prepared in a cheap an energy-efficient way and show high power conversion efficiencies already exceeding 20%. Not only high power conversion efficiencies but also solution processability at low temperature make perovskite solar cells a very attractive source of sustainable energy. The morphology of the perovskite films is one of the most critical issues to realize high efficient perovskite solar cells. Crucial process parameters to control the morphology of the perovskite films are the heating rate, annealing temperature and time.[1] They have also a great effect on the structural, electrical and optical properties of the perovskite material.[1,2,3]
In order to investigate the different annealing conditions, solar cells were built on a glass substrate with patterned indium tin oxide film (ITO) and have a configuration glass/ ITO/ c-TiOx/ mp-TiOx/ CH3NH3PbI3/ Spiro-OMeTAD/ Au. Different concentrations of the perovskite solution were used for the preparation of the perovskite film, where a 40 wt% stock solution was diluted 1:7, 1:6, 1:5 and 1:4 to obtain different concentrations. For further experiments, the dilution of 1:6 was taken because solar cells prepared with this precursor solution had the best power conversion efficiency (PCE), highest ISC and highest VOC. In the annealing temperature experiments the perovskite films were annealed at 70, 80, 90 and 100°C with a one-step method and from 70 to 100°C with a slow annealing multi-step methodas well as gradual heating at different rates. It was evident, that the solar cells annealed at 90°C had the best performance. The ISC is the only parameter which was higher at an annealing temperature of 100°C. This study also revealed, that the Isc is decreasing with decreasing annealing temperature. The other parameters like open circuit voltage, fill factor and PCE showed the highest values at an annealing temperature of 90°C. For the determination of the solar cell parameters, current voltage curves were measured and optical properties of the layers were characterized using UV/Vis spectroscopy. Characteristics like roughness, crystallinity, chemical composition, purity and morphology of the prepared perovskite ï¬lms were investigated by surface profilometry, X-ray diffraction and scanning electron microscopy.
References:
[1] Eperon GE et al., Adv. Funct. Mater., 24 (2014), pp. 151–157
[2] Dualeh A et al., 24 (2014), Adv. Funct. Mater., pp. 3250–3258
[3] Tripathi B et al., Sol. Energy Mater. Sol. Cells, 132 (2015), pp. 615–622