Graduate School of Engineering , Toin University of Yokohama , 1614 Kurogane-cho , Aoba, Yokohama , Kanagawa 225-8503 , Japan.
ACS Appl Mater Interfaces. 2018 Mar 21;10(11):9547-9554. doi: 10.1021/acsami.8b00430. Epub 2018 Mar 9.
Low stability of organic-inorganic lead halide perovskite and toxicity of lead (Pb) still remain a concern. Therefore, there is a constant quest for alternative nontoxic and stable light-absorbing materials with promising optoelectronic properties. Herein, we report about nontoxic bismuth triiodide (BiI) photovoltaic device prepared using TiO mesoporous film and spiro-OMeTAD as electron- and hole-transporting materials, respectively. Effect of annealing methods (e.g., thermal annealing (TA), solvent vapor annealing (SVA), and Petri dish covered recycled vapor annealing (PR-VA)) and different annealing temperatures (90, 120, 150, and 180 °C for PR-VA) on BiI film morphology have been investigated. As found in the study, grain size increased and film uniformity improved as temperature was raised from 90 to 150 °C. The photovoltaic devices based on BiI films processed at 150 °C with PR-VA treatment showed power conversion efficiency (PCE) of 0.5% with high reproducibility, which is, so far, the best PCE reported for BiI photovoltaic device employing organic hole-transporting material (HTM), owing to the increase in grain size and uniform morphology of BiI film. These devices showed stable performance even after 30 days of exposure to 50% relative humidity, and after 100 °C heat stress and 20 min light soaking test. More importantly, the study reveals many challenges and room (discussed in the details) for further development of the BiI photovoltaic devices.
有机-无机卤化铅钙钛矿的稳定性低和铅（Pb）的毒性仍然是一个关注点。因此，人们一直在寻求具有有前途的光电性能的替代无毒且稳定的光吸收材料。在此，我们报告了一种使用 TiO 介孔薄膜和 spiro-OMeTAD 分别作为电子和空穴传输材料制备的无毒三碘化铋（BiI）光伏器件。研究了退火方法（例如，热退火（TA）、溶剂蒸汽退火（SVA）和 Petri 盘覆盖回收蒸汽退火（PR-VA））和不同退火温度（PR-VA 为 90、120、150 和 180°C）对 BiI 薄膜形貌的影响。研究发现，随着温度从 90°C升高到 150°C，晶粒尺寸增大，薄膜均匀性提高。在 150°C 下用 PR-VA 处理的 BiI 薄膜制成的光伏器件显示出 0.5%的功率转换效率（PCE），具有很高的重现性，这是迄今为止使用有机空穴传输材料（HTM）报道的 BiI 光伏器件的最佳 PCE，这是由于 BiI 薄膜的晶粒尺寸增大和均匀形貌所致。这些器件在暴露于 50%相对湿度 30 天后，以及在 100°C 热应力和 20 分钟光浸泡测试后，仍表现出稳定的性能。更重要的是，该研究揭示了 BiI 光伏器件进一步发展的许多挑战和空间（在详细讨论中）。
