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Composition‐Tuned Wide Bandgap Perovskites: From Grain Engineering to Stability and Performance Improvement
Author(s) -
Zhou Yang,
Jia YongHeng,
Fang HongHua,
Loi Maria Antonietta,
Xie FangYan,
Gong Li,
Qin MinChao,
Lu XinHui,
Wong ChingPing,
Zhao Ni
Publication year - 2018
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.201803130
Subject(s) - materials science , band gap , perovskite (structure) , passivation , grain boundary , energy conversion efficiency , crystallization , open circuit voltage , phase (matter) , grain size , optoelectronics , photovoltaic system , chemical engineering , nanotechnology , voltage , microstructure , composite material , electrical engineering , chemistry , organic chemistry , layer (electronics) , engineering
Wide bandgap (WB) organic–inorganic hybrid perovskites (OIHPs) with a bandgap ranging between 1.7 and 2.0 eV have shown great potential to improve the efficiency of single‐junction silicon or thin‐film solar cells by forming a tandem structure with one of these cells or with a narrow bandgap perovskite cell. However, WB‐OIHPs suffer from a large open‐circuit voltage ( V oc ) deficit in photovoltaic devices, which is associated with the phase segregation of the materials under light illumination. In this work the photoinstability is demonstrated and V oc loss can be addressed by combining grain crystallization and grain boundary passivation, achieved simultaneously through tuning of perovskite precursor composition. Using FA 0.17 Cs 0.83 PbI 3– x Br x ( x = 0.8, 1.2 1.5, and 1.8), with a varied bandgap from 1.72 to 1.93 eV, as the model system it is illustrated how precursor additive Pb(SCN) 2 should be matched with a proper ratio of FAX (I and Br) to realize large grains with defect‐healed grain boundaries. The optimized WB‐OIHPs show good photostability at both room‐temperature and elevated temperature. Moreover, the corresponding solar cells exhibit excellent photovoltaic performances with the champion V oc /stabilized power output efficiency reaching 1.244 V/18.60%, 1.284 V/16.51%, 1.296 V/15.01%, and 1.312 V/14.35% for WB‐OIHPs with x = 0.8, 1.2, 1.5, and 1.8, respectively.