Identification of lead vacancy defects in lead halide perovskites

Journal article

Perovskite photovoltaics advance rapidly, but questions remain regarding point defects: while experiments have detected the presence of electrically active defects no experimentally confirmed microscopic identifications have been reported. Here we identify lead monovacancy (VPb) defects in MAPbI3 (MA = CH3NH3+) using positron annihilation lifetime spectroscopy with the aid of density functional theory. Experiments on thin film and single crystal samples all exhibited dominant positron trapping to lead vacancy defects, and a minimum defect density of ~3 7 1015 cm−3 was determined. There was also evidence of trapping at the vacancy complex (VPbVI)− in a minority of samples, but no trapping to MA-ion vacancies was observed. Our experimental results support the predictions of other first-principles studies that deep level, hole trapping, VPb2−, point defects are one of the most stable defects in MAPbI3. This direct detection and identification of a deep level native defect in a halide perovskite, at technologically relevant concentrations, will enable further investigation of defect driven mechanisms

Authors: Keeble, DJ; Wiktor, J; Pathak, SK; Phillips, LJ; Dickmann, M

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: Nature Research
• Journal: Nature Communications
• Volume: 12
• Issue: 1
• Pages: 5566-5566
• Article number: 5566
• Publication date: 2021-09-22
• DOI: 10.1038/s41467-021-25937-1
• EISSN: 2041-1723
• ISSN: 2041-1723
• Language: English
• Keywords: Materials science