Theoretical Investigations on Donor鈥揂cceptor Conjugated Copolymers Based on Naphtho[1,2-c:5,6-c]bis[1,2,5]thiadiazole for Organic Solar Cell Applications

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• 作者：Linghai Zhang ; Ke Pei ; Mudan Yu ; Yuanling Huang ; Hongbo Zhao ; Min Zeng ; Yang Wang ; Jinwei Gao
• 刊名：The Journal of Physical Chemistry C
• 出版年：2012
• 出版时间：December 20, 2012
• 年：2012
• 卷：116
• 期：50
• 页码：26154-26161
• 全文大小：468K
• 年卷期：v.116,no.50(December 20, 2012)
• ISSN：1932-7455

文摘

Conjugated polymers with donor鈥揳cceptor architectures have been successfully applied in bulk heterojunction solar cell devices. Tuning the electron-withdrawing capability in donor鈥揳cceptor (D鈥揂) conjugated polymers allows for design of new polymers with enhanced electrical and optical properties. In this paper, a series of D鈥揂 copolymers, PBDFDTBT (P1a), PBDTDTBT (P2a), PNDTDTBT (P3a), and PQDTDTBT (P4a), were selected and theoretically investigated using PBE0/6-311G** and TD-PBE0/6-311G**//PBE0/6-311G** methods. The calculated results agree well with the available experimental data of HOMO energy levels and band gaps. We further designed and studied four novel copolymers, P1b, P2b, P3b, and P4b, by substituting the 2,1,3-benzothiadiazole (BT) unit in P1a鈥揚4a with a stronger unit of naphtho[1,2-c:5,6-c]bis[1,2,5]thiadiazole (NT), respectively. Compared with P1a鈥揚4a, the newly designed polymers of P1b鈥揚4b show better performance with the smaller band gaps and lower HOMO energy levels. The PCEs of 5%, 7%, 7%, and 7% for P1b鈥揚4b, predicted by Scharber diagrams, are much higher than those of P1a鈥揚4a when used in combination with PCBM. These results clearly reveal that tuning the electron-withdrawing capability in D鈥揂 conjugated polymers is an effective way to improve the electrical and optical properties and the efficiency of the photovoltaic device.