Solvents incubated π-π stacking in hole transport layer for perovskite-silicon 2-terminal tandem solar cells with 27.21% efficiency

Room temperature sputtered inorganic nickel oxide (NiOx) is one of the most promising hole transport layers (HTL) for perovskite-sillion 2-terminal tandem solar cells with the aid of ultrathin and compact organic layers to passivate the surface defects. In this study, the aromatic solvent with different substituent groups was used to regulate the conformation of poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA) layer. As a result, the single-junction perovskite solar cell (PSC) gained a power conversion efficiency (PCE) of 20.63%, contributing to a 27.21% efficiency for monolithic perovskite/silicon (double-side polished) 2-terminal tandem solar cell, by applying the alkyl aromatic solvent to enhance the π-π stacking of PTAA molecular chains. The tandem solar cell can maintain 95% initial efficiency after aging over 1000 h. This study provides a universal approach for improving the photovoltaic performance of NiOx/polymer-based perovskite/silicon tandem solar cells and other single junction inverted PSCs.