Parallel Planar Heterojunction Strategy Enables Sb2S3 Solar Cells with Efficiency Exceeding 8

Solution‐processed solar cells based on inorganic heterojunctions provide a potential approach to the efficient, stable and low‐cost solar cells required for the terrestrial generation of photovoltaic energy. Antimony trisulfide (Sb2S3) is a promising photovoltaic absorber. Here, an easily solution‐processed parallel planar heterojunction (PPHJ) strategy and related principle are developed to prepare efficient multiple planar heterojunction (PHJ) solar cells, and the PPHJ strategy boosts the efficiency of solution‐processed Sb2S3 solar cells up to 8.32 % that is the highest amongst Sb2S3 devices. The Sb2S3‐based PPHJ device consists of two kinds of conventional planar heterojunction (PHJ) subcells in a parallel connection: Sb2S3‐based PHJ subcells dominating the absorption and charge generation and CH3NH3PbI3‐based PHJ subcells governing the electron transport towards collection electrode, but it belongs to an Sb2S3 device in nature. The resulting PPHJ device combines together the distinctive structural features of Sb2S3 absorbing layer as a main absorber and the duplexity of well‐crystallized/oriented CH3NH3PbI3 layer in charge transportation as an additional absorber, while the presence of perovskite does not affect device stability. The PPHJ strategy maintains the facile preparation by the conventional sequential depositions of multiple layers, but eliminates the normal complexity in both tandem and parallel tandem PHJ systems. An easily solution‐processed parallel planar heterojunction (PPHJ) strategy boosts the efficiency of Sb2S3 solar cells up to 8.32 %, by integrating the distinctive structures of Sb2S3 layer and the duplexity of CH3NH3PbI3 layer in charge transportation. The PPHJ device consists of the conventional planar heterojunction (PHJ) subcells in a parallel connection, but eliminates the normal complexity in both tandem and parallel tandem PHJ systems.