title: Vacuum-deposited small-molecule organic solar cells with high power conversion efficiencies by judicious molecular design and device optimization.
abstract: Three new tailor-made molecules (DPDCTB, DPDCPB, and DTDCPB) were strategically designed and convergently synthesized as donor materials for small-molecule organic solar cells. These compounds possess a donor-acceptor-acceptor molecular architecture, in which various electron-donating moieties are connected to an electron-withdrawing dicyanovinylene moiety through another electron-accepting 2,1,3-benzothiadiazole block. The molecular structures and crystal packings of DTDCPB and the previously reported DTDCTB were characterized by single-crystal X-ray crystallography. Photophysical and electrochemical properties as well as energy levels of this series of donor molecules were thoroughly investigated, affording clear structure-property relationships. By delicate manipulation of the trade-off between the photovoltage and the photocurrent via molecular structure engineering together with device optimizations, which included fine-tuning the layer thicknesses and the donor:acceptor blended ratio in the bulk heterojunction layer, vacuum-deposited hybrid planar-mixed heterojunction devices utilizing DTDCPB as the donor and C(70) as the acceptor showed the best performance with a power conversion efficiency (PCE) of 6.6 ± 0.2% (the highest PCE of 6.8%), along with an open-circuit voltage (V(oc)) of 0.93 ± 0.02 V, a short-circuit current density (J(sc)) of 13.48 ± 0.27 mA/cm(2), and a fill factor (FF) of 0.53 ± 0.02, under 1 sun (100 mW/cm(2)) AM 1.5G simulated solar illumination.
authors: Department of Materials Science and Engineering, National Tsing Hua University, Hsin Chu 30013, Taiwan.
authors: Yi-Hong
authors: YH
authors: Chen
authors: Li-Yen
authors: LY
authors: Lin
authors: Chih-Wei
authors: CW
authors: Lu
authors: Francis
authors: F
authors: Lin
authors: Zheng-Yu
authors: ZY
authors: Huang
authors: Hao-Wu
authors: HW
authors: Lin
authors: Po-Han
authors: PH
authors: Wang
authors: Yi-Hung
authors: YH
authors: Liu
authors: Ken-Tsung
authors: KT
authors: Wong
authors: Jianguo
authors: J
authors: Wen
authors: Dean J
authors: DJ
authors: Miller
authors: Seth B
authors: SB
authors: Darling