Role of Polymer Fractionation in Energetic Losses and Charge Carrier Lifetimes of Polymer: Fullerene Solar Cells

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• 作者：Derya Baran ; Michelle S. Vezie ; Nicola Gasparini ; Florent Deledalle ; Jizhong Yao ; Bob C. Schroeder ; Hugo Bronstein ; Tayebeh Ameri ; Thomas Kirchartz ; Iain McCulloch ; Jenny Nelson ; Christoph J. Brabec
• 刊名：Journal of Physical Chemistry C
• 出版年：2015
• 出版时间：August 27, 2015
• 年：2015
• 卷：119
• 期：34
• 页码：19668-19673
• 全文大小：340K
• ISSN：1932-7455

文摘

Nonradiative recombination reduces the open-circuit voltage relative to its theoretical limit and leads to reduced luminescence emission at a given excitation. Therefore, it is possible to correlate changes in luminescence emission with changes in open-circuit voltage and in the charge carrier lifetime. Here we use luminescence studies combined with transient photovoltage and differential charging analyses to study the effect of polymer fractionation in indacenoedithiophene-co-benzothiadiazole (IDTBT):fullerene solar cells. In this system, polymer fractionation increases electroluminescence emission at the same injection current and reduces nonradiative recombination. High-molecular-weight and fractionated IDTBT polymers exhibit higher carrier lifetime鈥搈obility product compared to that of their nonfractionated analogues, resulting in improved solar cell performance.