Strategy to Modulate the Electron-Rich Units in Donor鈥揂cceptor Copolymers for Improvements of Organic Photovoltaics

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• 作者：Xiaorui Liu ; Wei Shen ; Rongxing He ; Yafei Luo ; Ming Li
• 刊名：Journal of Physical Chemistry C
• 出版年：2014
• 出版时间：August 7, 2014
• 年：2014
• 卷：118
• 期：31
• 页码：17266-17278
• 全文大小：612K
• ISSN：1932-7455

文摘

We present an effective strategy to modulate the electron-rich capability in donor鈥揳cceptor (D-A) polymers for improving the performances of organic solar cell (OSC) devices. In order to confirm this strategy, based on a series of the reported D鈥揂 polymers ((PCPDTBT(Pa1), PCPDTFBT (Pa2), and PCPDTDFBT (Pa3)) which contain the electron-donating cyclopentadithiophene (CPDT) and differently electron-withdrawing units of benzo[c][1,2,5,]thiadiazole (BT), 5-fluorobenzo[c][1,2,5]thiadiazole (FBT), and 5,6-difluorobenzo[c] [1,2,5]thiadiazole (DFBT), we replace CPDT with electron-donating dithienogermolodithiophene (DTTG) in polymers Pa1鈥揚a3, respectively, and design a series of new D鈥揂 polymers Pb1鈥揚b3. Compared with the polymers Pa1鈥揚a3, the new designed polymers Pb1鈥揚b3 not only yield a greater red-shift of the absorption spectrum of the donor polymer and result in a larger absorption region within the solar emission spectrum and an improved light-absorbing efficiency but also exhibit much better electron transfer efficiency in active layer, larger hole transport rates and higher open circuit voltage. Moreover, the estimated power conversion efficiency of the designed polymers in OSC applications reaches up to 8.4%. Conclusively, the approach based on modulating the electron-donating capability in D鈥揂 polymer chain is a feasible way to enhance their intrinsic properties of donor polymers and thereby achieving the purpose that improves the performances of the OSC devices.