One-Step Synthesis of Precursor Oligomers for Organic Photovoltaics: A Comparative Study between Polymers and Small Molecules

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• 作者：Wei Li ; Daojuan Wang ; Suhao Wang ; Wei Ma ; Svante Hedstr枚m ; David Ian James ; Xiaofeng Xu ; Petter Persson ; Simone Fabiano ; Magnus Berggren ; Olle Ingan盲s ; Fei Huang ; Ergang Wang
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2015
• 出版时间：December 16, 2015
• 年：2015
• 卷：7
• 期：49
• 页码：27106-27114
• 全文大小：619K
• ISSN：1944-8252

文摘

Two series of oligomers TQ and rhodanine end-capped TQ-DR were synthesized using a facile one-step method. Their optical, electrical, and thermal properties and photovoltaic performances were systematically investigated and compared. The TQ series of oligomers were found to be amorphous, whereas the TQ-DR series are semicrystalline. For the TQ oligomers, the results obtained in solar cells show that as the chain length of the oligomers increases, an increase in power conversion efficiency (PCE) is obtained. However, when introducing 3-ethylrhodanine into the TQ oligomers as end groups, the PCE of the TQ-DR series of oligomers decreases as the chain length increases. Moreover, the TQ-DR series of oligomers give much higher performances compared to the original amorphous TQ series of oligomers owing to the improved extinction coefficient (蔚) and crystallinity afforded by the rhodanine. In particular, the highly crystalline oligomer TQ5-DR, which has the shortest conjugation length shows a high hole mobility of 0.034 cm² V^鈥? s^鈥? and a high PCE of 3.14%, which is the highest efficiency out of all of the six oligomers. The structure鈥損roperty correlations for all of the oligomers and the TQ1 polymer demonstrate that structural control of enhanced intermolecular interactions and crystallinity is a key for small molecules/oligomers to achieve high mobilities, which is an essential requirement for use in OPVs.