title: Fine-tuning device performances of small molecule solar cells via the more polarized DPP-attached donor units.
abstract: Three solution-processable small molecules of DPPT, DPPSe and DPPTT were synthesized by Stille coupling through attaching donor units of thiophene (T), selenophene (Se) and thieno[3,2-b]thiophene (TT) to the diketopyrrolopyrrole (DPP) core, respectively. Replacement of the T donors with the more polarized Se units results in a balance between the a and b direction packing and an obvious increase of the power conversion efficiency (PCE) from 1.90% to 2.33% with the increase of the short-circuit current (I(sc)) from 5.59 to 5.81 mA cm(-2) and the open-circuit voltage (V(oc)) from 0.78 V to 0.86 under the small molecule/acceptor ratio of 3 : 1. However, introduction of the conjugation-enlarged TT groups (versus the T units) leads to a decrease of the PCE, down to 1.70%, with a significant decrease of the fill factor (FF) (38% versus 44%), due to its poor film-forming characteristics.
authors: Beijing National Laboratory of Molecular Science, Institute of Chemistry, Chinese Academy of Sciences, PR China.
authors: Jianhua
authors: J
authors: Huang
authors: Hui
authors: H
authors: Jia
authors: Liangjie
authors: L
authors: Li
authors: Zhenhuan
authors: Z
authors: Lu
authors: Wenqing
authors: W
authors: Zhang
authors: Weiwei
authors: W
authors: He
authors: Bo
authors: B
authors: Jiang
authors: Ailing
authors: A
authors: Tang
authors: Zhan'ao
authors: Z
authors: Tan
authors: Chuanlang
authors: C
authors: Zhan
authors: Yongfang
authors: Y
authors: Li
authors: Jiannian
authors: J
authors: Yao