Fundamental Carrier Lifetime Exceeding 1 µs in Cs 2 AgBiBr 6 Double Perovskite

作者：Robert L. Z. Hoye, Lissa Eyre, Fengxia Wei, Federico Brivio, Aditya Sadhanala, Shijing Sun, Weiwei Li, Kelvin H. L. Zhang, Judith L. MacManus‐Driscoll, Paul D. Bristowe, Richard H. Friend, Anthony K. Cheetham, Felix Deschler · 发表于：Advanced Materials Interfaces · 年份：2018 · DOI：10.1002/admi.201800464 · 被引用次数：240 · 研究领域：Perovskite Materials and Applications、Chalcogenide Semiconductor Thin Films、Quantum Dots Synthesis And Properties

Abstract There is current interest in finding nontoxic alternatives to lead‐halide perovskites for optoelectronic applications. Silver–bismuth double perovskites have recently gained attention, but evaluating their carrier lifetime and recombination mechanisms from photoluminescence measurements is challenging due to their indirect bandgap. In this work, transient absorption spectroscopy is used to directly track the photocarrier population in Cs 2 AgBiBr 6 by measuring the ground state bleach dynamics. A small initial drop is resolved in the ground state bleach on a picosecond timescale, after which the remaining photocarriers decay monoexponentially with a lifetime of 1.4 µs. The majority of the early‐time decay is attributed to hot‐carrier thermalization from the direct transition to the indirect bandgap, and the 1.4 µs lifetime represents the recombination of most photocarriers. From this lifetime, a steady‐state excess carrier density of 2.2 × 10 16 cm −3 under 1 sun is calculated, which is an order of magnitude larger than that for methylammonium lead iodide, suggesting that charge transport and extraction can be efficient in Cs 2 AgBiBr 6 solar cells.