Boosting the Efficiency of SnO2‐Triple Cation Perovskite System Beyond 20% Using Nonhalogenated Antisolvent

• Published in: Advanced functional materials 2019-08, Vol.29 (32), p.n/a
• Main Authors: Lee, Hock Beng, Jeon, Mi‐Kyung, Kumar, Neetesh, Tyagi, Barkha, Kang, Jae‐Wook
• Format: Article
• Language: English
• Subjects: Carrier recombination; Cations; Crack propagation; Crystal growth; Efficiency; Energy conversion efficiency; Ethyl acetate; Grain boundaries; Grain size; halogenated; hysteresis; Materials science; passivation; Passivity; Perovskites; Photovoltaic cells; Solar cells; Stability; Tin dioxide; Tin oxides
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.201903213

Solution‐processed triple‐cation perovskite solar cells (PSCs) rely on complex compositional engineering or delicate interfacial passivation to balance the trade‐off between cell efficiency and long‐term stability. Herein, the facile fabrication of highly efficient, stable, and hysteresis‐free tin oxide (SnO2)‐based PSCs is demonstrated with a champion cell efficiency of 20.06% using a green, halogen‐free antisolvent. The antisolvent, composed of ethyl acetate (EA) solvent and hexane (Hex) in different proportions, works exquisitely in regulating perovskite crystal growth and passivating grain boundaries, leading to the formation of a crack‐free perovskite film with enlarged grain size. The high quality perovskite film inhibits carrier recombination and substantially improves the cell efficiency, without requiring an additional enhancer/passivation layer. Furthermore, these PSCs also demonstrate remarkable long‐term stability, whereby unencapsulated cells exhibit a power conversion efficiency (PCE) retention of ≈71% after >1500 hours of storage under ambient condition. For encapsulated cells, an astounding PCE retention of >98% is recorded after >3000 hours of storage in air. Overall, this work realizes the fabrication of SnO2‐based PSCs with a performance greater or comparable to the state‐of‐the‐art PSCs produced with halogenated antisolvents. Evidently, EA–Hex antisolvent can be an extraordinary halogen‐free alternative in maximizing the performance of PSCs. Eliminating the use of toxic, halogenated antisolvents in perovskite film preparation has been long desired. This work demonstrates the use of a halogen‐free, mixed antisolvent composed of ethyl acetate and hexane to boost the efficiency of tin oxide (SnO2)–triple cation system beyond 20% without the use of an additional passivation layer.