Stable semi-transparent CH3NH3PbI3 planar sandwich solar cells†
Semi-transparent CH3NH3PbI3 (MAPbI3) planar sandwich solar cells could be fabricated by simply laminating an FTO (F doped tin oxide)/TiO2/MAPbI3/wet hole transporting material (HTM) with additives and PEDOT:PSS (poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid))/indium tin oxide (ITO). The best FTO/TiO2/MAPbI3/P3HT with additives/PEDOT:PSS/ITO planar sandwich structured solar cells exhibited a 12.8% (deviation: 11.7% ± 0.74%) average power conversion efficiency (ηavg) but poor visible transmittance due to strong absorption by P3HT. Meanwhile, the semi-transparent FTO/TiO2/MAPbI3/PTAA with additives/PEDOT:PSS/ITO planar sandwich solar cells exhibited a 15.8% (deviation: 14.45% ± 0.76%) ηavg without significant J–V hysteresis with respect to the forward and reverse scan directions. The average visible transmittance (AVT) was controlled from 17.3% to 6.3% and the corresponding ηavg changed from 12.55% to 15.8%. The unsealed sandwich planar perovskite solar cells exhibited great air and humidity stability over 20 days due to the self-passivated device architecture of the sandwich type device.