Solution-Processed DPP-Based Small Molecule that Gives High Photovoltaic Efficiency with Judicious Device Optimization

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• 作者：Jianhua Huang ; Chuanlang Zhan ; Xin Zhang ; Yan Zhao ; Zhenhuan Lu ; Hui Jia ; Bo Jiang ; Jian Ye ; Shanlin Zhang ; Ailing Tang ; Yunqi Liu ; Qibing Pei ; Jiannian Yao
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2013
• 出版时间：March 27, 2013
• 年：2013
• 卷：5
• 期：6
• 页码：2033-2039
• 全文大小：433K
• 年卷期：v.5,no.6(March 27, 2013)
• ISSN：1944-8252

文摘

A solution-processed diketopyrrolopyrrole (DPP)-based small molecule, namely BDT-DPP, with broad absorption and suitable energy levels has been synthesized. The widely used solvents of chloroform (CF) and o-dichlorobenzene (o-DCB) were used as the spin-coating solvent, respectively, and 1,8-diiodooctane (DIO) was used as additive to fabricate efficient photovoltaic devices with BDT-DPP as the donor material and PC71BM as the acceptor material. Devices fabricated from CF exhibit poor fill factor (FF) of 43%, low short-circuit current density (J_sc) of 6.86 mA/cm², and moderate power conversion efficiency (PCE) of 2.4%, due to rapid evaporation of CF, leading to poor morphology of the active layer. When 0.3% DIO was added, the FF and J_sc were improved to 60% and 8.49 mA/cm², respectively, because of the better film morphology. Active layer spin-coated from the high-boiling-point solvent of o-DCB shows better phase separation than that from CF, because of the slow drying nature of o-DCB, offering sufficient time for the self-organization of active-layer. Finally, using o-DCB as the parent solvent and 0.7% DIO as the cosolvent, we obtained optimized devices with continuous interpenetrating network films, affording a J_sc of 11.86 mA/cm², an open-circuit voltage (V_oc) of 0.72 V, an FF of 62%, and a PCE of 5.29%. This PCE is, to the best of our knowledge, the highest efficiency reported to date for devices prepared from the solution-processed DPP-based small molecules.

Keywords:

solution-processed small molecules; diketopyrrolopyrrole; organic solar cells; device optimization