Kumar Pushpendra, Pal Suman Kalyan
School of Basic Sciences and Advanced Materials Research Center, Indian Institute of Technology Mandi , Kamand, Mandi 175005, Himachal Pradesh, India.
J Phys Chem A. 2015 Oct 1;119(39):10067-75. doi: 10.1021/acs.jpca.5b04109. Epub 2015 Sep 17.
Structural, electronic, and optical properties of a new coumarin dye, zinc oxide (ZnO) nanoclusters of varying sizes, and their complexes have been investigated using density functional theory (DFT). The band gap of oxide nanoclusters varies with size validating quantum confinement effect in small particles. Energy level diagrams of dye, ZnO nanoclusters, and redox electrolyte are in favor of efficient electron injection from dye to nanocluster and regeneration of the ionized dye. The adsorption of the organic dye to nanocluster is tested for anchoring through three different functional groups (cyano, carbonyl, and hydroxyl) of the dye. We have compared simulated absorption spectra of the dye, nanoclusters, and dye functionalized nanoclusters and discussed the matching with the solar irradiance spectrum. A strong new band appeared in the low energy side of the absorption spectra for dye adsorbed nanoclusters. Frontier molecular orbital calculations reveal that the first absorption band of dye-ZnO complexes is charge transfer (CT) in character. Excitation of this band leads to direct electron transfer to the conduction band (CB) of the nanocluster, making dye-ZnO complexes suitable for type II DSSCs as well.
利用密度泛函理论（DFT）研究了一种新型香豆素染料、不同尺寸的氧化锌（ZnO）纳米团簇及其复合物的结构、电子和光学性质。氧化物纳米团簇的带隙随尺寸变化，验证了小颗粒中的量子限域效应。染料、ZnO纳米团簇和氧化还原电解质的能级图有利于染料向纳米团簇的有效电子注入以及离子化染料的再生。通过染料的三种不同官能团（氰基、羰基和羟基）测试了有机染料对纳米团簇的吸附，以实现锚定。我们比较了染料、纳米团簇和染料功能化纳米团簇的模拟吸收光谱，并讨论了与太阳辐照光谱的匹配情况。对于染料吸附的纳米团簇，在吸收光谱的低能侧出现了一个强的新带。前沿分子轨道计算表明，染料-ZnO复合物的第一吸收带具有电荷转移（CT）特征。该带的激发导致直接电子转移到纳米团簇的导带（CB），这也使得染料-ZnO复合物适用于II型染料敏化太阳能电池（DSSC）。
