Stabilized tilted-octahedra halide perovskites inhibit local formation of performance-limiting phases

DOI: 10.1126/science.abl4890

Authors: Tiarnan A. S. Doherty (University of Cambridge) , Satyawan Nagane (Department of Physics, Cavendish Laboratory) , Dominik J. Kubicki (University of Cambridge) , Young-Kwang Jung (Yonsei University) , Duncan N. Johnstone (University of Cambridge) , Affan N. Iqbal (University of Cambridge) , Dengyang Guo (University of Cambridge) , Kyle Frohna (University of Cambridge) , Mohsen Danaie (Diamond Light Source; University of Oxford) , Elizabeth M. Tennyson (University of Cambridge) , Stuart Macpherson (University of Cambridge) , Anna Abfalterer (University of Cambridge) , Miguel Anaya (University of Cambridge) , Yu-Hsien Chiang (University of Cambridge) , Phillip Crout (University of Cambridge) , Francesco Simone Ruggeri (Wageningen University and Research) , Sean M. Collins (University of Leeds) , Clare P. Grey (University of Cambridge) , Aron Walsh (Yonsei University; Imperial College London) , Paul A. Midgley (University of Cambridge) , Samuel D. Stranks (University of Cambridge)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Science , VOL 374 , PAGES 1598 - 1605

State: Published (Approved)
Published: December 2021
Diamond Proposal Number(s): 20420 , 24111

Abstract: Efforts to stabilize photoactive formamidinium (FA)–based halide perovskites for perovskite photovoltaics have focused on the growth of cubic formamidinium lead iodide (α-FAPbI3) phases by empirically alloying with cesium, methylammonium (MA) cations, or both. We show that such stabilized FA-rich perovskites are noncubic and exhibit ~2° octahedral tilting at room temperature. This tilting, resolvable only with the use of local nanostructure characterization techniques, imparts phase stability by frustrating transitions from photoactive to hexagonal phases. Although the bulk phase appears stable when examined macroscopically, heterogeneous cation distributions allow microscopically unstable regions to form; we found that these transitioned to hexagonal polytypes, leading to local trap-assisted performance losses and photoinstabilities. Using surface-bound ethylenediaminetetraacetic acid, we engineered an octahedral tilt into pure α-FAPbI3 thin films without any cation alloying. The templated photoactive FAPbI3 film was extremely stable against thermal, environmental, and light stressors.

Diamond Keywords: Photovoltaics; Semiconductors

Subject Areas: Materials, Energy, Physics

Diamond Offline Facilities: Electron Physical Sciences Imaging Centre (ePSIC)
Instruments: E02-JEM ARM 300CF , I14-Hard X-ray Nanoprobe

Added On: 28/12/2021 15:53

Discipline Tags:

Surfaces Earth Sciences & Environment Sustainable Energy Systems Energy Physics Climate Change Energy Materials Materials Science interfaces and thin films Perovskites Metallurgy

Technical Tags:

Diffraction Microscopy Electron Microscopy (EM) Transmission Electron Microscopy (TEM)