Elucidating the Factors Limiting the Photovoltaic Performance of Mixed Sb-Bi Halide Elpasolite Absorbers
Elucidating the Factors Limiting the Photovoltaic Performance of Mixed Sb-Bi Halide Elpasolite Absorbers
复制标题
阐明限制混合锑铋卤化物钾冰晶石吸收器光伏性能的因素
作者：
Li Z
虽然Cs2 AgBiBr 6卤化物钙钛矿作为铅卤化物钙钛矿的潜在无毒和稳定的替代品已经获得了大量的关注，但它们受到>2.2 eV的宽带隙的限制。已证明将Sb合金化到磷属元素位置中是降低带隙的有效方法，但这并没有转化为光伏（PV）性能的改善。在此，调查的根本原因。Cs2 Ag（SbxBi 1 −x）Br 6的无针孔薄膜是通过抗溶剂滴落实现的，但PV器件的功率转换效率仍从0.44% ± 0.02%（不含Sb）降至0.073% ± 0.007%（90% Sb;最低带隙）。开路电压降低了0.7 V，这与含Sb的钾镁矾膜中光学带隙以下约0.7 eV的亚带隙状态的出现相关，如在吸光度和光致发光测量中所发现的。通过详细的Williamson-Hall分析，发现在钾长石薄膜中加入Sb会导致薄膜应变的增加。这种应变通过气溶胶辅助溶剂处理来缓解，这降低了薄膜中的亚带隙态密度和能量无序，以及减少了由于陷阱填充而导致的光生载流子群的快速早期衰减。这项工作表明，Sb合金化导致引入额外的亚带隙状态，这限制了PV性能，但可以通过后退火处理来减轻，以减少无序和应变。
Although Cs2AgBiBr6halide elpasolites have gained substantial attention as potential nontoxic and stable alternatives to lead–halide perovskites, they are limited by their wide bandgaps >2.2 eV. Alloying with Sb into the pnictogen site has been shown to be an effective method to lower the bandgap, but this has not translated into improvements in photovoltaic (PV) performance. Herein, the underlying causes are investigated. Pinhole‐free films of Cs2Ag(SbxBi1−x)Br6are achieved through antisolvent dripping, but PV devices still exhibit a reduction in power conversion efficiency from 0.44% ± 0.02% (without Sb) to 0.073% ± 0.007% (90% Sb; lowest bandgap). There is a 0.7 V reduction in the open‐circuit voltage, which correlates with the appearance of a sub‐bandgap state ≈0.7 eV below the optical bandgap in the Sb‐containing elpasolite films, as found in both absorbance and photoluminescence measurements. Through detailed Williamson–Hall analysis, it is found that adding Sb into the elpasolite films leads to an increase in film strain. This strain is relieved through aerosol‐assisted solvent treatment, which reduces both the sub‐bandgap state density and energetic disorder in the films, as well as reducing the fast early decay in the photogenerated carrier population due to trap filling. This work shows that Sb alloying leads to the introduction of extra sub‐bandgap states that limit the PV performance, but can be mitigated through post‐annealing treatment to reduce disorder and strain.