Abstract
AbstractThere 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 Cs2AgBiBr6 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 × 1016 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 Cs2AgBiBr6 solar cells.
Highlights
There is current interest in finding nontoxic alternatives to lead-halide perovsmotivated researchers to find lead-free alterkites for optoelectronic applications
Time-resolved photoluminescence (TRPL) measurements of these materials show an initial drop in photoluminescence (PL) over a nanosecond
Increases in the efficiency of perovskite solar cells[5] and light emitting than methylammonium lead iodide,[18,20] they have attracted sigdiodes (>11% external quantum efficiency)[6] over a short period nificant interest, with many recent investigations of new families of time
Summary
There is current interest in finding nontoxic alternatives to lead-halide perovsmotivated researchers to find lead-free alterkites for optoelectronic applications. The optimized thin films had a lower Urbach energy than the Cs2AgBiBr6 single crystal, and a low sub-bandgap absorption coefficient (Figure S7, Supporting Information).
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