New -(D-A₁-D-A₂)_n- type conjugated polymers for photovoltaic applications: consensus between low band-gap and low HOMO energy level

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• 作者：Xiaolian Hu ; Weifei Fu ; Lijian Zuo ; Hangqi Shi ; Meirong Chen ; Shiyong Liu ; Junying Pan ; Lei Fu ; Minmin Shi ; ^{minminshi@zju.edu.cn} ; Hongzheng Chen
• 关键词：Polymer solar cells ; Diketopyrrolopyrrole ; Donor&ndash ; acceptor ; Electron withdrawing ; HOMO
• 刊名：Tetrahedron
• 出版年：2013
• 出版时间：22 April, 2013
• 年：2013
• 卷：69
• 期：16
• 页码：3419-3424
• 全文大小：697 K

文摘

To gain ideal conjugated polymers with a low band-gap (E_g) and a deep HOMO (highest occupied molecular orbital) energy level for photovoltaic application, both strong and weak electron withdrawing units were introduced into polymer backbone. A series of -(D-A₁-D-A₂)_n- type diketopyrrolopyrrole (DPP) containing polymers P1-P7 were designed and synthesized. The resulting copolymers exhibited both low E_g of 1.27-1.48?eV and deep HOMO energy levels of ?5.25to ?5.44?eV. Preliminary photovoltaic properties of the copolymers blended with [6,6]-phenyl-C₆₁-butyric acid methyl ester (PCBM) were investigated. All photovoltaic devices featured high open circuit voltages (V_oc, 0.72-0.91?V). Among the seven copolymers, P5 exhibited the best performance with a V_oc of 0.80?V, a short circuit current density (I_sc) of 3.48?mA/cm², a fill factor (FF) of 43.2 % , and a power conversion efficiency (PCE) of 1.33 % .