Azar Yavar T, Payami Mahmoud
Theoretical and Computational Physics Group, School of Physics and Accelerators, AEOI, P. O. Box 14395-836, Tehran, Iran.
Phys Chem Chem Phys. 2014 May 28;16(20):9499-508. doi: 10.1039/c4cp00598h.
In this work, using the DFT and TDDFT, we have theoretically studied the electronic and optical properties of the two recently synthesized coadsorbents Y1 and Y2, which were aimed to enhance the efficiency of the black dye-sensitized solar cells. To determine the solvatochromic shifts, both the implicit and mixed implicit-explicit models have been used. The connection between the solvatochromic shifts and the changes in dipole moments in the excitation process is discussed. The difference in excitation charge transfer is utilized to explain the experimentally observed difference in Jsc for Y1 and Y2. Investigating the interactions of I2 molecules in the electrolyte solution with the coadsorbents showed that with Y1 the recombination loss was weakened through decreasing the I2 concentration near the TiO2 surface, whereas with Y2 it was increased. As a result, the higher values of both Jsc and Voc with the Y1 coadsorbent explain its experimentally observed higher efficiency. The present study sheds light on how to design and engineer newer coadsorbents or organic dyes for higher efficiencies.
在本工作中，我们使用密度泛函理论（DFT）和含时密度泛函理论（TDDFT）从理论上研究了两种最近合成的共吸附剂Y1和Y2的电子和光学性质，其目的是提高黑色染料敏化太阳能电池的效率。为了确定溶剂化显色位移，我们使用了隐式模型和混合隐式-显式模型。讨论了溶剂化显色位移与激发过程中偶极矩变化之间的联系。利用激发电荷转移的差异来解释实验观察到的Y1和Y2短路电流密度（Jsc）的差异。研究电解质溶液中I2分子与共吸附剂的相互作用表明，对于Y1，通过降低TiO2表面附近的I2浓度减弱了复合损失，而对于Y2则增加了复合损失。结果，使用Y1共吸附剂时Jsc和开路电压（Voc）的较高值解释了其实验观察到的较高效率。本研究阐明了如何设计和制造更高效率的新型共吸附剂或有机染料。
