Is There a Polaron Signature in Angle-Resolved Photoemission of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi>CsPbBr</mml:mi></mml:mrow><mml:mrow><mml:mn>3</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>?
Maryam Sajedi, Maxim Krivenkov, D. Marchenko, J. Sánchez‐Barriga, Anoop K. Chandran, A. Varykhalov, E. D. L. Rienks, Irene Aguilera, Stefan Blügel, O. Rader
Abstract
The formation of large polarons has been proposed as reason for the high defect tolerance, low mobility, low charge carrier trapping, and low nonradiative recombination rates of lead halide perovskites. Recently, direct evidence for large-polaron formation has been reported from a 50% effective mass enhancement in angle-resolved photoemission of ${\mathrm{CsPbBr}}_{3}$ over theory for the orthorhombic structure. We present in-depth band dispersion measurements of ${\mathrm{CsPbBr}}_{3}$ and GW calculations, which lead to similar effective masses at the valence band maximum of $0.203\ifmmode\pm\else\textpm\fi{}0.016$ ${m}_{0}$ in experiment and 0.226 ${m}_{0}$ in orthorhombic theory. We argue that the effective mass can be explained solely on the basis of electron-electron correlation and large-polaron formation cannot be concluded from photoemission data.