Proceedings of nanoGe September Meeting 2015 (NFM15)
Publication date: 8th June 2015
In order to establish renewable-energy society, fabrication of cost-effective solar cells is necessary, otherwise the electricity fee for our living life will be increased (in Germany, already the electricity fee became double). Despite the rapid increase in photovoltaic module, the price is still expensive due to the vacuum processing. For the printed solar cells, several devises have been fabricated; dye-sensitized solar cells, organic thin-film solar cells, and Pb-perovskite solar cells. However, these solar cells are composed of carbon double-bond materials, which can react with oxygen and water under irradiation. Here, we report printed solar cells without carbon double bond: Pb perovskite solar cells with CuSCN as p-type hole-transporting material and crystalline-silicon solar cells without SiNx. The perovskite CH3NH3PbI3 combined with CuSCN as p-type HTM lead to solar cells with very high power conversion efficiency (12.4%) under full sun illumination. Moreover, to improve the stability, Sb2S3 layers were inserted at the interface between TiO2 and CH3NH3PbI3 perovskite to be CH3NH3PbI3 solar cells using inorganic hole transporting material (CuSCN). During the light exposure test without encapsulation, the CH3NH3PbI3 solar cells without Sb2S3 deteriorated to zero efficiency in 12 h and were completely changed from black to yellow, because the perovskite CH3NH3PbI3 was changed to hexagonal PbI2. With Sb2S3, on the other hand, the CH3NH3PbI3 solar 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 TiO2 and CH3NH3PbI3. About the crystalline silicon solar cells, we have fabricated the solar cells using single-crystalline silicon wafers without vacuum system, resuiting in 16.5% conversion efficiency. In place of SiNx anti-reflection layer, TiO2 and Al2O3 layers have been coated by spray pyrolysis deposition (SPD). We found very interesting phenomena of the SPD TiO2 and Al2O3 layers, which are helpful for the application to be the cost effective solar cells.