Improving Photovoltaic Performance Using Perovskite/Surface-Modified Graphitic Carbon Nitride Heterojunction

摘要

Passivation strategies are considered as one of the most efficient methods tosuppress nonradiative recombination of organic–inorganic lead halide perovskitesolar cells (PSCs), leading to tremendous photovoltaic performance. An innovative2D polymer, graphitic carbon nitride (g-C_3N_4), as well as various organicgroups (amino, sulfonic, nitrato, and hydroxy group), are widely used as passivationagents, according to the previous reports. Anchoring g-C3N4 and theaforementioned organic groups as additives in perovskite can both heal chargeddefects around the grain boundaries by passivating the charge recombinationcenter. In addition, the crystalline quality can also be enhanced by the incorporationof g-C_3N_4, leading to improved conductivity of perovskite light absorberfilms that is beneficial for benign charge extraction efficiency. Inspired by theunderlining mechanisms, a series of novel passivation molecules, functionalizedg-C_3N_4 (F-C_3N_4) with assorted organic groups, is designed herein, yielding achampion power conversion efficiency (PCE) of 20.08% for NO_3-C_3N_4-based p-i-nstructure PSC, in comparison with that of PSC without passivation (17.85%).These findings present an efficient strategy to understand and design multiplefacets of applications of novel passivation molecules to further improve the PCEof PSCs.