Excited-State and Charge Carrier Dynamics in a High-Photovoltage and Thermostable Dye-Sensitized Solar Cell
Excited-State and Charge Carrier Dynamics in a High-Photovoltage and Thermostable Dye-Sensitized Solar Cell
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高光电压和热稳定染料敏化太阳能电池中的激发态和载流子动力学
DOI：
10.1021/acsphotonics.6b00772
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发表时间：
2017-01-01
期刊：
影响因子：
7
通讯作者：
Wang, Peng
中科院分区：
文献类型：
--
作者：
Chen, Shu;Yang, Lin;Wang, Peng
除了收集更多的红外太阳光子以获得更高的光电流之外，提高染料敏化太阳能电池的光电压和热稳定性是其性能增强的另外两个关键挑战性问题。本文报道了一种以三苯胺-二己基联噻吩为电子给体和苯并噻二唑-苯甲酸为电子受体的无金属给体-受体染料（SC-4）。该有机染料可用于制造敏化二氧化钛太阳能电池，当分别应用挥发性三（1，10-菲咯啉）钴基电解质和非挥发性碘基离子液体复合电解质时，该敏化二氧化钛太阳能电池分别表现出1005和825 mV的优异光电压。相对于使用传统电子受体氰基丙烯酸的对照染料C239，染料SC-4不仅由于较慢的界面电荷复合而显示出增强的光电压，而且由于染料分子从二氧化钛表面的可忽略的解吸，即使在85 ℃的长期热老化下也显示出改善的光电流稳定性和效率。染料敏化太阳能电池在热应力下的光电压降首次被确定为二氧化钛和电解质之间的界面的固有不稳定性，这需要在未来的研究中明智地钝化。超快PL测量和理论计算揭示了有机染料的多个非平衡激发态发生扭转能量弛豫和电子注入，导致电子注入的高度分布动力学。
Apart from the harvesting of more infrared solar photons for a higher photocurrent, improving the photovoltage and thermal stability of a dye-sensitized solar cell are the other two key challenging issues for its performance enhancement. Herein we report a metal-free donor-acceptor dye (SC-4) characteristic of a triphenylamine-dihexylbithiophene electron donor and a benzothiadiazole-benzoic acid electron acceptor. This organic dye can be utilized for the fabrication of sensitized titania solar cells exhibiting excellent photovoltages of 1005 and 825 mV, respectively, when a volatile tris(1,10-phenanthroline)cobalt-based electrolyte and a nonvolatile iodine-based ionic liquid composite electrolyte are applied, respectively. With respect to the control dye C239 using the traditional electron acceptor cyanoaciylic acid, dye SC-4 displays not only an enhanced photovoltage owing to slower interfacial charge recombination but also an improved stability of photocurrent and efficiency even under a long-term thermal aging at 85 degrees C, because of negligible desorption of dye molecules from the surface of titania. The photovoltage drop of dye-sensitized solar cells under the thermal stress is identified for the first time as the intrinsic instability of the interface between titania and electrolyte, which needs to be judiciously passivated in a future study. Ultrafast PL measurements and theoretical calculations have unveiled that torsional energy relaxation and electron injection occur from the multiple nonequilibrium excited states of organic dyes, resulting in a highly distributive kinetics of electron injection.