Diketo-pyrrolo-pyrrole-Based Medium Band Gap Copolymers for Efficient Plastic Solar Cells: Morphology, Transport, and Composition-Dependent Photovoltaic Behavior

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• 作者：Lin Chen ; Dan Deng ; Yaxiong Nan ; Minmin Shi ; Paddy K. L. Chan ; Hongzheng Chen
• 刊名：Journal of Physical Chemistry C
• 出版年：2011
• 出版时间：June 9, 2011
• 年：2011
• 卷：115
• 期：22
• 页码：11282-11292
• 全文大小：1218K
• 年卷期：v.115,no.22(June 9, 2011)
• ISSN：1932-7455

文摘

Two diketo-pyrrolo-pyrrole-based donor鈥揳cceptor copolymers, PCPDT鈥揚DPP and PDTP鈥揚DPP, were synthesized and applied as p-type component for bulk heterojunction solar cells. Using a facile molecular engineering of the main chain linking bridge, we have successfully tuned the band gap of the materials from low to medium level, which results in an improved balance between the device open circuit voltage and short circuit current. The power conversion efficiencies of the polymer/PC₇₀BM combinations achieve 2.03% (PCPDT鈥揚DPP) and 1.32% (PDTP鈥揚DPP) without any interface engineering or post-treatment. A totally different composition-dependent photovoltaic behavior was also discovered for each of the two materials, although they share similar donor鈥揳cceptor (D鈥揂) structure. Morphological and photophysical studies reveal a phase structure dominated, light harvesting subordinated mechanism, in which some nonkernel molecular level factors, such as the branch chain density and the molecular weight, are found to play important roles.