Effect of Dual Cathode Buffer Layer on the Charge Carrier Dynamics of rrP3HT:PCBM Based Bulk Heterojunction Solar Cell

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• 作者：Ashish Singh ; Anamika Dey ; Dipjyoti Das ; Parameswar Krishnan Iyer
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2016
• 出版时间：May 4, 2016
• 年：2016
• 卷：8
• 期：17
• 页码：10904-10910
• 全文大小：572K
• 年卷期：0
• ISSN：1944-8252

文摘

In bulk heterojunction (BHJ) solar cells, the buffer layer plays a vital role in enhancing the power conversion efficiency (PCE) by improving the charge carrier dynamics. A comprehensive understanding of the contacts is especially essential in order to optimize the performance of organic solar cells (OSCs). Although there are several fundamental reports on this subject, a proper correlation of the physical processes with experimental evidence at the photoactive layer and contact materials is essential. In this work, we incorporated three different additional buffer layers, namely, tris(8-hydroxyquinolinato) aluminum (Alq3), bathophenanthroline (BPhen) or bathocuproine (BCP) with LiF/Al as conventional cathode contact in both rrP3HT:PC₆₁BM and rrP3HT:PC₇₁BM blend BHJ solar cells and their corresponding photovoltaic performances were systematically correlated with their energy level diagram. The device with dual cathode buffer layer having ITO/PEDOT:PSS/blend polymer/BCP/LiF/Al configuration showed the best device performance with PCE, η = 4.96%, J_sc = 13.53 mA/cm², V_oc = 0.60 V and FF= 61% for rrP3HT:PC₇₁BM and PCE, η = 4.5% with J_sc = 13.3 mA/cm², V_oc = 0.59 V and FF = 59% for rrP3HT:PC₆₁BM. This drastic improvement in PCE in both the device configurations are due to the combined effects of better hole-blocking capacity of BCP and low work function provided by LiF/Al with the blend polymer. These results successfully explain the role of dual cathode buffer layers and their contribution to the PCE improvement and overall device performance with rrP3HT:PCBM based BHJ solar cell.