Degradation mechanism for planar heterojunction perovskite solar cells

Abstract

Abstract Organic–inorganic hybrid perovskite materials have recently emerged as a promising cost- and energy-efficient light absorber material for photovoltaic applications. Unfortunately, perovskite solar cells have a problem with decreasing power conversion efficiency owing to their degradation in air. To clarify the cause of the degradation of perovskite solar cells, we exposed deposited CH 3 NH 3 PbI 3 and HC(NH 2 ) 2 PbI 3 films to an O 2 or (H 2 O+N 2 ) atmosphere condition. Analysis of these films revealed that a large energy band gap was observed as a result of the influence of the H 2 O molecule in CH 3 NH 3 PbI 3 and HC(NH 2 ) 2 PbI 3 . Under the (H 2 O+N 2 ) atmosphere condition, the existence of CH 3 NH 3 I and HC(NH 2 ) 2 I molecules was found to affect the morphology and as well as the crystalline diffraction peak. The resultant perovskite crystalline structure was degraded by H 2 O molecules under the air exposure condition.