Investigation of Hole-Transporting Poly(triarylamine) on Aggregation and Charge Transport for Hysteresisless Scalable Planar Perovskite Solar Cells

Organometallic halide perovskite solar cells (PSCs) have unique photovoltaic properties for use in next-generation solar energy harvesting systems. The highest efficiency of PSCs reached 22.1% on a laboratory scale of <0.1 cm(2) device area. Thus, scaling up is the next step toward commercialization, but the difficulty in controlling the quality of large area perovskite thin films remains a fundamental challenge. It has also been frequently reported that the J-V hysteresis is intensified in PSCs with areas larger than 1 cm(2). In this study, we have fabricated a large-area perovskite layer using PbICl films, providing an intrinsic porous layer and enhancing the uniformity of the perovskite layer at areas larger than 1 cm(2). Furthermore, we have investigated the polymeric properties of the prevalent hole-transporting material poly(triarylamine) (PTAA) with its photovoltaic performance. Two types of PTAAs, poly[bis(4-phenyl)(2,4-dimethylphenyl)amine] and poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine], were compared. A series of PTAAs with different molecular weights (M-w) and polydispersity indices were studied, as the molecular weight of the PTAA is a key factor in determining the electrical properties and photovoltaic performance of the system. The fabricated PSCs with an aperture area of 1 cm(2) based on a high-molecular-weight PTAA achieved a power conversion efficiency of 16.47% with negligible hysteresis and excellent reproducibility.