Next-generation and solution-processed thin-film solar cells have been attracted considerable attention because of their low cost, light weight, flexibility, and aesthetics. However, most of solution-processed thin-film solar cells are now focused on the use of photovoltaic absorbers containing the toxic element of Pb. In this study, eco-friendly silver-bismuth-iodide (Ag-Bi-I) thin-film photovoltaic devices with high open-circuit voltages (V_OC) are developed by utilizing polythieno[3,4-b]-thiophene-co-benzodithiophene (PTB7) as the hole transport layer (HTL). The solution-processed AgBi₂I₇ semiconductor, which is an Ag-Bi-I ternary compound, exhibit features suitable for photovoltaic layers in thin-film solar cells, including a three-dimensional (3D) crystal structure, good surface morphology, and low optical bandgaps of 1.87 eV. Meanwhile, the solution-processed AgBi₂I₇ thin-film solar cell based on the PTB7 HTL exhibit a power conversion efficiency of 0.94% with an improved V_OC value of 0.71 V owing to the deeper highest occupied molecular orbital (HOMO) energy level compared to that of poly(3-hexylthiophene-2,5-diyl) (P3HT). In other words, the V_OC of the PTB7 HTL-based device is 20% higher than that of the P3HT HTL-based control device. Our results provide a new approach for increasing the V_OC of eco-friendly Ag-Bi-I thin-film photovoltaics and indicate that further HTL engineering is necessary to simultaneously improve the V_OC and performance of the devices.

Graphical Abstract

中文翻译：

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具有 PTB7 聚合物基空穴传输层的生态友好型碘化银铋薄膜光伏器件的增强开路电压

下一代和溶液处理的薄膜太阳能电池因其低成本、重量轻、柔韧性和美观性而受到广泛关注。然而，大多数溶液处理的薄膜太阳能电池现在都集中在使用含有有毒元素铅的光伏吸收剂上。在这项研究中，利用聚噻吩并[3,4- b ]-噻吩-co开发了具有高开路电压（ V _OC）的环保型碘化银铋（Ag-Bi-I）薄膜光伏器件- 苯并二噻吩 (PTB7) 作为空穴传输层 (HTL)。溶液处理的 AgBi ₂ I ₇半导体是一种 Ag-Bi-I 三元化合物，具有适用于薄膜太阳能电池中光伏层的特性，包括三维 (3D) 晶体结构、良好的表面形态和 1.87 eV 的低光学带隙。同时，基于 PTB7 HTL 的溶液处理 AgBi ₂ I ₇薄膜太阳能电池表现出 0.94% 的功率转换效率，并且由于更深的最高占据分子轨道 (HOMO) 能级，V _OC值提高了 0.71 V与聚（3-己基噻吩-2,5-二基）(P3HT) 相比。换句话说，V _OC基于 PTB7 HTL 的设备比基于 P3HT HTL 的控制设备高 20%。我们的结果为提高环保型 Ag-Bi-I 薄膜光伏器件的V _{OC提供了一种新方法，并表明需要进一步的 HTL 工程来同时提高}V _OC和器件性能。

图形概要