Efficiency enhancement of semi-transparent sandwich type CH₃NH₃PbI₃ perovskite solar cells with island morphology perovskite film by introduction of polystyrene passivation layer

Highly semi-transparent sandwich type CH₃NH₃PbI₃ (MAPbI₃) island perovskite solar cells with high efficiency were constructed by introduction of a polystyrene (PS) passivation interlayer. The PS insulator can prevent direct contact between the TiO₂ electron conductor and the polytriarylamine hole conductor. The PS passivation interlayer could be selectively deposited on bare TiO₂ by a consecutive spin-coating and spin-washing process. The average visible transmittance of semi-transparent sandwich type MAPbI₃ island perovskite solar cells with and without PS passivation layer was ∼20.9% and ∼18.6%, respectively; its power conversion efficiency was 10.2% for forward scan condition and 10.6% for reverse scan condition (average = 6.17% ± 2.32% for 40 samples) and 5.9% for forward scan condition and 6.6% for reverse scan condition (average = 2.93% ± 1.57% for 40 samples); and its efficiency degradation for 30 days was ∼5% and ∼9%, respectively.