Identification of lead vacancy defects in lead halide perovskites

TY - JOUR

T1 - Identification of lead vacancy defects in lead halide perovskites

AU - Keeble, David

AU - Wiktor, Julia

AU - Pathak, Sandeep K.

AU - Phillips, Laurie J.

AU - Dickmann, Marcel

AU - Durose, Ken

AU - Snaith, Henry J.

AU - Egger, Werner

N1 - D.J.K. gratefully acknowledges the financial support provided by FRM-II to perform the high-intensity positron beam measurements at Heinz Maier-Leibnitz Zentrum (MLZ), Garching, Germany. J.W. acknowledges funding from the "Area of Advance - Materials Science'' at Chalmers University of Technology and the Swedish Research Council (2019-03993). The computations were partly performed on resources provided by the Swedish National Infrastructure for Computing (SNIC) at NSC and PDC. L.J.P. and K.D. would like to acknowledge support from EPSRC grants EP/N014057/1m and E. H.J.S. acknowledges support from EPSRC grant EP/L024667/1. W.E. gratefully acknowledges BMBF-grants 05K13WN1-POSIANALYSE, 05K16WN1-POSITEC and 05K19WN1-POSILIFE of the German Federal Office of Research and Education.

PY - 2021/9/22

Y1 - 2021/9/22

N2 - 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 (V Pb) defects in MAPbI 3 (MA = CH 3NH 3 +) 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 × 10 15 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 MAPbI 3. 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.

AB - 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 (V Pb) defects in MAPbI 3 (MA = CH 3NH 3 +) 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 × 10 15 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 MAPbI 3. 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.

KW - Photovoltaics

KW - Semiconductors

UR - https://www.scopus.com/pages/publications/85115387078

U2 - 10.1038/s41467-021-25937-1

DO - 10.1038/s41467-021-25937-1

M3 - Article

C2 - 34552098

SN - 2041-1723

VL - 12

JO - Nature Communications

JF - Nature Communications

M1 - 5566

ER -