Device Performance Related to Amphiphilic Modification at Charge Separation Interface in Hybrid Solar Cells with Vertically Aligned ZnO Nanorod Arrays

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• 作者：Dongqin Bi ; Fan Wu ; Qiyun Qu ; Wenjin Yue ; Qi Cui ; Wei Shen ; Ruiqiang Chen ; Changwen Liu ; Zeliang Qiu ; Mingtai Wang
• 刊名：Journal of Physical Chemistry C
• 出版年：2011
• 出版时间：March 10, 2011
• 年：2011
• 卷：115
• 期：9
• 页码：3745-3752
• 全文大小：909K
• 年卷期：v.115,no.9(March 10, 2011)
• ISSN：1932-7455

文摘

This paper reports the chemical modification effects at charge separation interface on the performance of the hybrid solar cells consisting of poly(2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene) (MEH-PPV) as an electron donor (D) and vertically aligned ZnO nanorod arrays as an electron acceptor (A). Results show that, with increasing the modification time T_s for grafting dye Z907 onto the ZnO surface from 0 to 8 h, the charge transfer efficiency at the MEH-PPV/ZnO interface keeps increasing, the short circuit current (J_sc) increases and reaches a peak value at T_s = 8 h, but the open circuit voltage (V_oc) increases within T_s = 1鈭? h and reduces with further increasing T_s up to 鈮? h. By controlling the T_s, a peak power conversion efficiency of 畏 = 0.61% at AM 1.5 illumination (100 mW/cm²) is obtained for T_s = 6 h. It is revealed that the Z907 modification mainly contributes to the enhanced J_sc by increasing the charge separation efficiency as a result of the improved electronic coupling property at the D/A interface rather than the light harvesting; on the other hand, the Z907 modification reduces (T_s = 1鈭? h) or increases (T_s 鈮?6 h) the surface defect concentration of the ZnO nanorods, resulting in the increased or reduced V_oc (or electron lifetime 蟿_e). It is demonstrated that trapping electrons by the surface defects may facilitate the charge separation at the D/A interface in the MEH-PPV/ZnO devices, and both V_oc and 蟿_e correlate to the occupation of injected electrons in conduction band and surface defects. Further analysis provides the relation between V_oc and 蟿_e in those devices.