Solution-processable bismuth iodide nanosheets as hole transport layers for organic solar cells

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• 作者：Karunakara Moorthy Boopathi ; Sankar Raman ; Rajeshkumar Mohanraman ; Fang-Cheng Chou ; Yang-Yuang Chen ; Chih-Hao Lee ; Feng-Chih Chang ; Chih-Wei Chu
• 关键词：Bismuth iodide nanosheet ; Hole transport layer ; Low temperature ; Solution-processable ; Organic photovoltaics
• 刊名：Solar Energy Materials and Solar Cells
• 出版年：February, 2014
• 年：2014
• 卷：121
• 期：Complete
• 页码：35-41
• 全文大小：2657 K

文摘

In this paper we demonstrate the use of low-temperature-solution-processable bismuth iodide (BiI₃) nanosheets as hole transport layers in organic photovoltaics with an active layer comprising poly(3-hexylthiophene) (P3HT) mixed with a fullerene derivative. The performance of the resulting devices was comparable with that of corresponding conventionally used systems incorporating polyethylenedioxythiophene:polystyrenesulfonate (PEDOT:PSS). UV-vis spectroscopy revealed that the transparency of a BiI₃ layer in the visible (>620 nm) and near-infrared range is greater than that of a PEDOT:PSS layer. X-ray photoemission spectroscopy of a BiI₃ film revealed signals at 158.8, 164, 618.6, and 630 eV鈥攃haracteristic of Bi 4f_7/2, Bi 4f_5/2, I 3d_5/2, and I 3d_3/2, respectively鈥攖hat indicated a stoichiometric BiI₃ film. Wet milling of BiI₃ crystals resulted in the formation of nanosheets, the presence of which we confirmed using scanning electron microscopy. The resultant power conversion efficiency of the device was approximately 3.5%, with an open-circuit voltage of 0.56 V, a short-circuit current density of 10.4 mA cm^-2, and a fill factor of 60.1% under AM1.5G irradiation (100 mW cm^鈭?).