Molecular tailor-making of zinc phthalocyanines as dopant-free hole-transporting materials for efficient and stable perovskite solar cells

Abstract

Four Zinc (II) phthalocyanines (ZnPcs) derivatives, ZnPH13, ZnPH14, ZnPH15 and ZnPH22, decorated with elaborate molecular tailor-making on the phenyl-based peripheral substituents of Pc scaffolds are synthesized and acted as dopant-free hole-transporting materials (HTMs) in perovskite solar cells (PSCs). The detailed electrochemical, photophysical characteristics, theoretical geometric/electronic features, hole mobility, charge carrier extraction, collection and transporting dynamic processes of these HTMs are cautiously unveiled. The heuristic probe into the substantial relations and dependences between the Pc organic scaffold structure and properties at molecule level are investigated. The mixed-ion PSC utilizing the ZnPH22 containing the benzo[d] [1,3]dioxole peripheral substituent with cyclic/planar conformation presents a most competitive power conversion efficiency (PCE) of 18.3% associating with excellent reproducibility and superior long-period stability. These results reveal that the eventual solar cell performance can be decipherable through the intrinsic electronic and structural effects originating from the peripheral substituents modifications. This work thus exploits the new insights into the advanced molecular building of efficient phthalocyanines HTMs for high performance and stable PSCs.