RT Journal Article
SR Electronic
T1 Strong self-trapping by deformation potential limits photovoltaic performance in bismuth double perovskite
JF Science Advances
JO Sci Adv
FD American Association for the Advancement of Science
SP eabd3160
DO 10.1126/sciadv.abd3160
VO 7
IS 8
A1 Wu, Bo
A1 Ning, Weihua
A1 Xu, Qiang
A1 Manjappa, Manukumara
A1 Feng, Minjun
A1 Ye, Senyun
A1 Fu, Jianhui
A1 Lie, Stener
A1 Yin, Tingting
A1 Wang, Feng
A1 Goh, Teck Wee
A1 Harikesh, Padinhare Cholakkal
A1 Tay, Yong Kang Eugene
A1 Shen, Ze Xiang
A1 Huang, Fuqiang
A1 Singh, Ranjan
A1 Zhou, Guofu
A1 Gao, Feng
A1 Sum, Tze Chien
YR 2021
UL http://advances.sciencemag.org/content/7/8/eabd3160.abstract
AB Bismuth-based double perovskite Cs2AgBiBr6 is regarded as a potential candidate for low-toxicity, high-stability perovskite solar cells. However, its performance is far from satisfactory. Albeit being an indirect bandgap semiconductor, we observe bright emission with large bimolecular recombination coefficient (reaching 4.5 ± 0.1 × 10−11 cm3 s−1) and low charge carrier mobility (around 0.05 cm2 s−1 V−1). Besides intermediate Fröhlich couplings present in both Pb-based perovskites and Cs2AgBiBr6, we uncover evidence of strong deformation potential by acoustic phonons in the latter through transient reflection, time-resolved terahertz measurements, and density functional theory calculations. The Fröhlich and deformation potentials synergistically lead to ultrafast self-trapping of free carriers forming polarons highly localized on a few units of the lattice within a few picoseconds, which also breaks down the electronic band picture, leading to efficient radiative recombination. The strong self-trapping in Cs2AgBiBr6 could impose intrinsic limitations for its application in photovoltaics.