Nguyen The-Duy, Lan Yen-Po, Wu Chun-Guey
Research Center for New Generation Light Driven Photovoltaic Modules and Department of Chemistry, National Central University, Jhong-Li, 32001 Taiwan, Republic of China.
Inorg Chem. 2021 Aug 2;60(15):11328-11337. doi: 10.1021/acs.inorgchem.1c01293. Epub 2021 Jul 19.
Three thiocyanate-free cycloruthenated complexes, DUY24-O, DUY24, and DUY24-Se containing furan, thiophene, and selenophene, respectively, as a part of the cycloruthenated ring, were designed to reveal the function of the chalcogen atom on the physicochemical and photovoltaic performance of the cycloruthenated sensitizers applied in dye-sensitized solar cells (DSCs). The three sensitizers have a similar molecular size; therefore, the effect of molecular dimensions on their photovoltaic performance can be negligible. NMR data, electron-donating resonance effects, optical properties, and the energy levels of the frontier orbitals reveal that the physical/photovoltaic properties of the three sensitizers were affected significantly by the chalcogen atom on the cyclometalated chalcogenophene ring. The λ (both in ethanol and adsorbed on TiO), frontier orbital level, and dye loading of thiophene- and selenophene-containing dyes are very close. Nevertheless, DUY24-Se has a higher molar absorption coefficient compared to DUY24; therefore, the DSC based on DUY24-Se has higher efficiency (8.4% under AM1.5 G one-sun and 26% under T5-light at 6000 lux) than that sensitized with the DUY24 dye. These efficiencies are also higher than those (7.9 and 21.6%, respectively) of the cell dyed with N719, fabricated using the same conditions. The better performance of the device sensitized with DUY24-Se compared to DUY24-based cells suggests that selenophene is as good as (or even better than) thiophene to be a part of the cyclometalated ring for thiocyanate-free cycloruthenated sensitizers applied in DSCs. Furan-containing DUY24-O has much worse photovoltaic performance compared to the other two dyes. This is not only because DUY24-O has the shortest λ, the lowest molar absorption coefficient, and the highest HOMO level but also the lowest dye loading (because of the strong interaction between the oxygen in furan and TiO, the array of DUY24-O occupies more surface when adsorbed on TiO) and the fastest charge recombination. The physicochemical and photovoltaic properties as well as the adsorption behavior of the dye on the TiO anode for the cycloruthenated sensitizers affected significantly by the chalcogen atom of the chalcogenophene on the cyclometalated ring provide a new strategy to design high-efficiency NCS-free cyclometalated sensitizers for DSCs.
设计了三种无硫氰酸根的环钌配合物DUY24-O、DUY24和DUY24-Se，它们分别含有呋喃、噻吩和硒吩作为环钌环的一部分，以揭示硫族原子对应用于染料敏化太阳能电池（DSC）的环钌敏化剂的物理化学和光伏性能的影响。这三种敏化剂具有相似的分子尺寸；因此，分子尺寸对其光伏性能的影响可以忽略不计。核磁共振数据、给电子共振效应、光学性质和前沿轨道的能级表明，三种敏化剂的物理/光伏性质受到环金属化硫族吩环上硫族原子的显著影响。含噻吩和含硒吩染料的λ（在乙醇中和吸附在TiO上时）、前沿轨道能级和染料负载量非常接近。然而，与DUY24相比，DUY24-Se具有更高的摩尔吸收系数；因此，基于DUY24-Se的DSC具有更高的效率（在AM1.5 G一个太阳光照下为8.4%，在6000勒克斯的T5光下为26%），高于用DUY24染料敏化的DSC。这些效率也高于在相同条件下制备的用N719染色的电池的效率（分别为7.9%和21.6%）。与基于DUY24的电池相比，用DUY24-Se敏化的器件性能更好，这表明对于应用于DSC的无硫氰酸根环钌敏化剂来说，硒吩作为环金属化环的一部分与噻吩一样好（甚至更好）。与其他两种染料相比，含呋喃的DUY24-O的光伏性能要差得多。这不仅是因为DUY24-O的λ最短、摩尔吸收系数最低、HOMO能级最高，而且染料负载量最低（由于呋喃中的氧与TiO之间的强相互作用，DUY24-O的阵列在吸附在TiO上时占据更多表面）以及电荷复合最快。环金属化环上硫族吩的硫族原子对环钌敏化剂的物理化学和光伏性质以及染料在TiO阳极上的吸附行为有显著影响，这为设计用于DSC的高效无NCS环金属化敏化剂提供了一种新策略。
