Proceedings of 6th International Conference on Hybrid and Organic Photovoltaics (HOPV14)
Publication date: 1st March 2014
Carbon double bond-free printed solar cells have been fabricated with the structure < F-doped SnO2(FTO) /dense TiO2/nanocrystalline TiO2/CH3NH3PbI3/Au> and <FTO /dense TiO2/nanocrystalline TiO2/CH3NH3PbI3/CuSCN /Au>, where CuSCN acts as a hole conductor. The thickness of the CH3NH3PbI3layer was controlled by hot air flow during the spin coating. The best conversion efficiency (4.86%) was obtained with <FTO/dense TiO2/nanocrystalline TiO2/thin CH3NH3PbI3(hot air dried) /CuSCN/Au>. However, a thick CH3NH3PbI3layer on CuSCN was better for light-exposed stability (100 mW cm-2AM 1.5) when not encapsulated. Without the CuSCN coverage, the black CH3NH3PbI3crystal changed to yellow during the light-exposure stability test, which is due to the transformation of the CH3NH3PbI3perovskite crystal into hexagonal PbI2.
Sb2S3layers were inserted at the interface between TiO2and CH3NH3PbI3perovskite to be CH3NH3PbI3solar cells using inorganic hole transporting material (CuSCN). The CH3NH3PbI3 layer was spin-coated by one-drop method on nanocrystalline TiO2layer. The photoenergy conversion efficiencies were improved with Sb2S3layers (the best efficiency: 5.24%). During the light exposure test without encapsulation, the CH3NH3PbI3solar cells without Sb2S3deteriorated to zero efficiency in 12 h and were completely changed from black to yellow, because the perovskite CH3NH3PbI3was changed to hexagonal PbI2. With Sb2S3, on the other hand, the CH3NH3PbI3solar cells became stable against light exposure without encapsulation, which didn’t change the crystal structure and the wavelength edges of absorption and IPCE. Therefore, it was considered that the degradation can occur at the interface between TiO2and CH3NH3PbI3.