文献类型：期刊文献

英文题名：Constructing Organic D-A-π-A-Featured Sensitizers with a Quinoxaline Unit for High-Efficiency Solar Cells: The Effect of an Auxiliary Acceptor on the Absorption and the Energy Level Alignment

作者：Pei, Kai[1,2];Wu, Yongzhen[1,2];Wu, Wenjun[1,2];Zhang, Qiong[1,2];Chen, Baoqin[1,2];Tian, He[1,2];Zhu, Weihong[1,2]

机构：[1]E China Univ Sci & Technol, Key Lab Adv Mat, Shanghai Key Lab Funct Mat Chem, Shanghai 200237, Peoples R China;[2]E China Univ Sci & Technol, Inst Fine Chem, Shanghai 200237, Peoples R China

年份：2012

卷号：18

期号：26

起止页码：8190

外文期刊名：CHEMISTRY-A EUROPEAN JOURNAL

收录：;EI(收录号：20122615153733);WOS:【SCI-EXPANDED(收录号:WOS:000305388300029)】；

基金：This work was financially supported by NSFC/China, the Oriental Scholarship, Shanghai Shuguang Project (07SG34), SRFDP 200802510011, the Fundamental Research Funds for the Central Universities (WK1013002), and STCSM (10dz2220500).

语种：英文

外文关键词：absorption; electron lifetime; quinoxalines; sensitizers; solar cells

摘要：Four organic DAp-A-featured sensitizers (TQ1, TQ2, IQ1, and IQ2) have been studied for high-efficiency dye-sensitized solar cells (DSSCs). We employed an indoline or a triphenylamine unit as the donor, cyanoacetic acid as the acceptor/anchor, and a thiophene moiety as the conjugation bridge. Additionally, an electron-withdrawing quinoxaline unit was incorporated between the donor and the p-conjugation unit. These sensitizers show an additional absorption band covering the broad visible range in solution. The contribution from the incorporated quinoxaline was investigated theoretically by using DFT and time-dependent DFT. The incorporated low-band-gap quinoxaline unit as an auxiliary acceptor has several merits, such as decreasing the band gap, optimizing the energy levels, and realizing a facile structural modification on several positions in the quinoxaline unit. As demonstrated, the observed additional absorption band is favorable to the photon-to-electron conversion because it corresponds to the efficient electron transitions to the LUMO orbital. Electrochemical impedance spectroscopy (EIS) Bode plots reveal that the replacement of a methoxy group with an octyloxy group can increase the injection electron lifetime by a factor of 2.4. IQ2 and TQ2 can perform well without any co-adsorbent, successfully suppress the charge recombination from TiO2 conduction band to I3- in the electrolyte, and enhance the electron lifetime, resulting in a decreased dark current and enhanced open circuit voltage (Voc) values. By using a liquid electrolyte, DSSCs based on dye IQ2 exhibited a broad incident photon-to-current conversion efficiency (IPCE) action spectrum and high efficiency (?=8.50?%) with a short circuit current density (Jsc) of 15.65 mA?cm-2, a Voc value of 776 mV, a fill factor (FF) of 0.70 under AM 1.5 illumination (100 mW?cm-2). Moreover, the overall efficiency remained at 97?% of the initial value after 1000 h of visible-light soaking.