title: Solution-processed DPP-based small molecule that gives high photovoltaic efficiency with judicious device optimization.
abstract: 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 (Jsc) of 6.86 mA/cm(2), 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 Jsc were improved to 60% and 8.49 mA/cm(2), 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 Jsc of 11.86 mA/cm(2), an open-circuit voltage (Voc) 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.
authors: Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, PR China.
authors: Jianhua
authors: J
authors: Huang
authors: Chuanlang
authors: C
authors: Zhan
authors: Xin
authors: X
authors: Zhang
authors: Yan
authors: Y
authors: Zhao
authors: Zhenhuan
authors: Z
authors: Lu
authors: Hui
authors: H
authors: Jia
authors: Bo
authors: B
authors: Jiang
authors: Jian
authors: J
authors: Ye
authors: Shanlin
authors: S
authors: Zhang
authors: Ailing
authors: A
authors: Tang
authors: Yunqi
authors: Y
authors: Liu
authors: Qibing
authors: Q
authors: Pei
authors: Jiannian
authors: J
authors: Yao