Mechanistic insights into UV-induced electron transfer from PCBM to titanium oxide in inverted-type organic thin film solar cells using AC impedance spectroscopy.
Mechanistic insights into UV-induced electron transfer from PCBM to titanium oxide in inverted-type organic thin film solar cells using AC impedance spectroscopy.
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DOI：
10.1021/am100312v
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发表时间：
2010-07
影响因子：
9.5
通讯作者：
T. Kuwabara;Chiaki Iwata;T. Yamaguchi;Kohshin Takahashi
中科院分区：
文献类型：
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作者：
T. Kuwabara;Chiaki Iwata;T. Yamaguchi;Kohshin Takahashi
制备了一种以非晶二氧化钛（TiOx）为电子收集电极的倒置有机体异质结太阳能电池，其结构为ITO/TiO（x）/[6，6]-苯基C（61）丁酸甲酯（PCBM）：区域规整的聚（3-己基噻吩）（P3 HT）/聚（3，4-乙撑二氧乙烯基）：聚（4-苯乙烯磺酸）/Au（TiO（x）电池）。通过光电流-电压谱和交流阻抗谱研究了其复杂的光伏特性。TiO（x）电池需要大量的时间（约60分钟）来达到其2.6%的最大功率转换效率（PCE）。为了研究这种缓慢的光响应的原因，我们研究了UV光和吸附在TiO（x）层上的水分子的影响。表面处理的TiO（x）电池与水诱导快速的光响应，并提高了性能，得到的PCE为2.97%。然而，由于UV诱导的光降解，处理过的电池的耐久性显著劣于未处理的电池。处理后的电池的快速光响应的原因归因于吸附的水分子和靠近TiO（x）表面的PCBM中的羰基氧原子之间形成氢键。当TiO（x）表面被紫外光诱导的空穴带正电时，靠近TiO（x）表面的PCBM中的羰基氧可以快速地结合到TiO（x）表面，快速地将光生电子从PCBM传输到TiO（x）表面，与光催化降解竞争。实验结果表明，未处理的TiO（x）电池的光响应慢是由于光活性有机层的形貌在辐照后逐渐发生变化，从而改善了TiO（x）/PCBM：P3 HT界面上光生载流子的输运。
An inverted organic bulk-heterojunction solar cell containing amorphous titanium oxide (TiOx) as an electron collection electrode with the structure ITO/TiO(x)/[6,6]-phenyl C(61) butyric acid methyl ester (PCBM): regioregular poly(3-hexylthiophene) (P3HT)/poly(3,4-ethylenedioxylenethiophene):poly(4-styrene sulfonic acid)/Au (TiO(x) cell) was fabricated. Its complicated photovoltaic properties were investigated by photocurrent-voltage and alternating current impedance spectroscopy measurements. The TiO(x) cell required a significant amount of time (approximately 60 min) to reach its maximum power conversion efficiency (PCE) of 2.6%. To investigate the reason for this slow photoresponse, we investigated the influences of UV light and water molecules adsorbed on the TiO(x) layer. Surface treatment of the TiO(x) cell with water induced a rapid photoresponse and enhanced the performance, giving a PCE of 2.97%. However, the durability of the treated cell was considerably inferior that of the untreated cell because of UV-induced photodegradation. The cause of the rapid photoresponse of the treated cell was attributed to the formation of hydrogen bonds between adsorbed water molecules and carbonyl oxygen atoms in PCBM close to the TiO(x) surface. When the TiO(x) surface was positively charged by UV-induced holes, the carbonyl oxygen in PCBM close to the TiO(x) surface can quickly join to the TiO(x) surface, rapidly transporting photogenerated electrons from PCBM to TiO(x) in competition with the photocatalyzed degradation. The experimental results suggested that the slow photoresponse of the untreated TiO(x) cell was because the morphology of the photoactive organic layer changed gradually upon irradiation to improve the transport of photocarriers at the TiO(x)/PCBM:P3HT interface.