Saha Anusuya, Ganguly Bishwajit
Computation and Simulation Unit, Analytical and Environmental Science Division and Centralized Instrument Facility, CSIR-Central Salt & Marine Chemicals Research Institute, Bhavnagar, Gujarat, 364002, India.
Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India.
J Mol Model. 2022 Apr 27;28(5):131. doi: 10.1007/s00894-022-05111-0.
In this work, we report the lower stability of dyes containing cyanoacrylic acid anchoring group on semiconductor TiO surface compared to the corresponding silyl unit in dye-sensitized solar cell. Density functional theory (DFT) calculations have been performed with simple donor (N,N diphenylamine) and π-conjugated spacers, with silyl anchoring groups to examine the efficiency of DSSCs. The calculated results in CAM-B3LYP/6-31G(d)/CPCM(THF) reveal that the cyanoacrylic acid anchoring group would have weaker coordination on semiconductor TiO surface compared to the silyl anchoring group on the same surface. The designed dyes 1-7 exhibit comparable or in cases superior optical properties than that of the reference dye molecule with cyanoacrylic acid as an anchoring group. All designed dyes have lower ΔG values implying efficient and faster electron recombination between the dye and electrolyte. The electron transition coefficient for these dyes is higher enough (~72-87%) suggesting successful electron propagation from dye to the semiconductor. The electron-donating methyl and ethyl groups show lower ΔG values than the commonly studied -OEt substitution with the silyl anchoring group. The extended π conjugation for better electronic propagation and higher λ values have been achieved with simple ethylene and butadiene units in the dye molecules. Dye 7 with butadiene as π-spacer unit shows superior oscillatory strength (f) of 2.19 and light-harvesting efficiency (LHE) of 0.99 than the other studied dyes and reference dye with carboxylic anchoring group (TA-ST-CA). The lowest ΔG value (0.53 eV) of dye 7 suggests better electronic recombination than all the other dyes studied here. Transition Density matrix and PDOS calculations with the representative dye 7 suggest a good electronic propagation from the dye to the semiconductor. The incorporation of a highly π-conjugated spacer 4,8-di(thiophen-2-yl)-1H,5H-benzo[1,2-c:4,5-c']bis([1,2,5]thiadiazole) in dye 7 (7-BBT) showed remarkable enhancement in the absorption maxima ~800 nm corresponds to the UV-vis and NIR regions. The DFT calculated results shed light on designing new DSSCs with silyl anchoring groups for enhanced stability and superior efficiency.
在本工作中，我们报道了在染料敏化太阳能电池中，含氰基丙烯酸锚固基团的染料在半导体TiO表面的稳定性低于相应的硅烷基单元。使用简单供体（N,N -二苯胺）和π共轭间隔基以及硅烷基锚固基团进行了密度泛函理论（DFT）计算，以研究染料敏化太阳能电池的效率。在CAM - B3LYP/6 - 31G(d)/CPCM(THF)水平下的计算结果表明，与同一表面上的硅烷基锚固基团相比，氰基丙烯酸锚固基团在半导体TiO表面的配位作用较弱。所设计的染料1 - 7表现出与以氰基丙烯酸为锚固基团的参比染料分子相当的光学性质，在某些情况下甚至更优。所有设计的染料都具有较低的ΔG值，这意味着染料与电解质之间的电子复合效率高且速度快。这些染料的电子跃迁系数足够高（约72 - 87%），表明电子从染料成功传输到半导体。供电子的甲基和乙基的ΔG值低于常用的硅烷基锚固基团的 -OEt取代基。通过在染料分子中引入简单的乙烯和丁二烯单元，实现了更好的电子传输和更高的λ值的扩展π共轭。以丁二烯为π间隔基单元的染料7表现出比其他研究染料以及具有羧基锚固基团的参比染料（TA - ST - CA）更高的振子强度（f），为2.19，以及光捕获效率（LHE），为0.99。染料7的最低ΔG值（0.53 eV）表明其电子复合性能优于此处研究的所有其他染料。对代表性染料7进行的跃迁密度矩阵和PDOS计算表明，电子从染料到半导体有良好的传输。在染料7（7 - BBT）中引入高度π共轭的间隔基4,8 - 二（噻吩 - 2 - 基）-1H,5H - 苯并[1,2 - c:4,5 - c']双（[1,2,5]噻二唑）导致吸收最大值在约800 nm处显著增强，对应于紫外 - 可见和近红外区域。DFT计算结果为设计具有硅烷基锚固基团的新型染料敏化太阳能电池以提高稳定性和效率提供了思路。
