Slavney Adam H, Leppert Linn, Bartesaghi Davide, Gold-Parker Aryeh, Toney Michael F, Savenije Tom J, Neaton Jeffrey B, Karunadasa Hemamala I
Department of Chemistry, Stanford University , Stanford, California 94305, United States.
Molecular Foundry, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States.
J Am Chem Soc. 2017 Apr 12;139(14):5015-5018. doi: 10.1021/jacs.7b01629. Epub 2017 Apr 4.
Halide double perovskites have recently been developed as less toxic analogs of the lead perovskite solar-cell absorbers APbX (A = monovalent cation; X = Br or I). However, all known halide double perovskites have large bandgaps that afford weak visible-light absorption. The first halide double perovskite evaluated as an absorber, CsAgBiBr (1), has a bandgap of 1.95 eV. Here, we show that dilute alloying decreases 1's bandgap by ca. 0.5 eV. Importantly, time-resolved photoconductivity measurements reveal long-lived carriers with microsecond lifetimes in the alloyed material, which is very promising for photovoltaic applications. The alloyed perovskite described herein is the first double perovskite to show comparable bandgap energy and carrier lifetime to those of (CHNH)PbI. By describing how energy- and symmetry-matched impurity orbitals, at low concentrations, dramatically alter 1's band edges, we open a potential pathway for the large and diverse family of halide double perovskites to compete with APbX absorbers.
卤化物双钙钛矿最近已被开发出来，作为铅钙钛矿太阳能电池吸收剂APbX（A = 单价阳离子；X = Br或I）毒性较低的类似物。然而，所有已知的卤化物双钙钛矿都有较大的带隙，导致可见光吸收较弱。第一种被评估为吸收剂的卤化物双钙钛矿CsAgBiBr (1)，其带隙为1.95 eV。在此，我们表明稀释合金化使(1)的带隙降低了约0.5 eV。重要的是，时间分辨光电导率测量揭示了合金化材料中具有微秒寿命的长寿命载流子，这对于光伏应用非常有前景。本文所述的合金化钙钛矿是第一种带隙能量和载流子寿命与(CHNH)PbI相当的双钙钛矿。通过描述低浓度下能量和对称性匹配的杂质轨道如何显著改变(1)的能带边缘，我们为庞大且多样的卤化物双钙钛矿家族开辟了一条与APbX吸收剂竞争的潜在途径。
