Fundamental Carrier Lifetime Exceeding 1 µs in Cs2AgBiBr6 Double Perovskite. Issue 15 (22nd May 2018)

• Record Type: Journal Article
• Authors: Hoye, Robert L. Z.; Eyre, Lissa; Wei, Fengxia; Brivio, Federico; Sadhanala, Aditya; Sun, Shijing; Li, Weiwei; Zhang, Kelvin H. L.; MacManus‐Driscoll, Judith L.; Bristowe, Paul D.; Friend, Richard H.; Cheetham, Anthony K.; Deschler, Felix
• Is Part Of: Advanced materials interfaces. Volume 5:Issue 15(2018)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2018-05-22
• Subjects: defect recombination -- double perovskite -- lifetime -- time‐resolved photoluminescence -- transient absorption spectroscopy; Materials science -- Periodicals; 620.11
• DOI: 10.1002/admi.201800464
• Languages: English
• ISSNs: 2196-7350

Abstract

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 Cs2 AgBiBr6 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 Cs2 AgBiBr6 solar cells. Abstract : Cs2 AgBiBr6 thin film is identified to have a fundamental photocarrier lifetime of 1.4 µs. Both the lifetime and the 1 sun steady‐state carrier population in this lead‐free material exceed those in lead–halide perovskite thin films, suggesting that efficient carrier transport and extraction can be achieved in photovoltaic devices.