Strain relaxation and domain enlargement via phase transition towards efficient CsPbI2Br solar cells. Issue 7 (19th January 2022)

• Record Type: Journal Article
• Authors: Qiu, Fa-Zheng; Li, Ming-Hua; Wang, Shuo; Jiang, Yan; Qi, Jun-Jie; Hu, Jin-Song
• Is Part Of: Journal of materials chemistry. Volume 10:Issue 7(2022)
• Page Start: 3513
• Page End: 3521
• Publication Date: 2022-01-19
• Subjects: Materials -- Research -- Periodicals; Chemistry, Analytic -- Periodicals; Environmental sciences -- Research -- Periodicals; 543.0284
• DOI: 10.1039/d1ta09180h
• Languages: English
• ISSNs: 2050-7488

Abstract

Abstract : We propose a phase transition growth strategy for the deposition of CsPbI2 Br films that allows relaxation of the tensile strain by 62 ± 4% and reduction of defect densities at the film surface and in bulk. PSCs achieve an efficiency of 16.5%. Abstract : CsPbI2 Br perovskite is emerging as an attractive photovoltaic material due to its excellent stability against heat and illumination. However, a huge tensile stress of about 162 MPa is created during the CsPbI2 Br film formation, resulting in a high defect density, severe non-radiation recombination loss and instability of CsPbI2 Br PSCs. Herein, an α → δ → α phase transition growth (PTG) approach is developed for the deposition of CsPbI2 Br films that allows relaxation of the relative tensile strain by 62 ± 4% and increases the domain size by 800%. The CsPbI2 Br films realize a low defect density of 5.59 × 10 15 cm −3 and a reduced Urbach energy. PSCs prepared by the PTG approach achieve a PCE of 16.5% with a remarkably high V oc of 1.36 V. These CsPbI2 Br PSCs retain 90% of their initial efficiency after storage under 10–15% relative humidity (RH) conditions for 1200 h and 90% of their initial efficiency after heating at 65 °C for 800 h.