摘要
采用密度泛函理论(DFT)和含时密度泛函理论(TD-DFT)对四种二氢吲哚染料进行研究,从中筛选出相对优秀的染料敏化太阳能电池光敏剂.对前线分子轨道的计算表明,二氢吲哚染料的前线分子轨道结构非常有利于染料激发态向TiO2电极的电子注入.对真空中的紫外和可见光吸收光谱的计算表明,二氢吲哚染料的吸收光谱与太阳辐射光谱匹配较好.对染料分子的能级计算表明,二氢吲哚染料的能级结构比较适合于I-/I-3作电解液的TiO2纳米晶太阳能电池的光敏剂.二氢吲哚染料最低未占据分子轨道(LUMO)能级均比TiO2晶体导带边能级高,能够保证激发态染料分子高效地向TiO2电极转移电子.二氢吲哚染料最高占据分子轨道(HOMO)的能级比I-/I3-能级低,保证了失去电子的染料分子能够顺利地从电解液中得到电子.与实验数据比较,得出在提高染料敏化太阳能电池转换效率方面,对染料的关键要求是LUMO能级的位置.染料分子的稳定性是染料敏化太阳能电池使用寿命的关键因素.通过对化学键键长的比较表明,二氢吲哚染料的分子稳定性基本相同.对计算结果的分析表明,二氢吲哚染料1(ID1)的LUMO能级最高,分子稳定性最好,在酒精溶液中的吸收光谱与太阳辐射光谱匹配很好,在同类染料中是较好的染料敏化太阳能电池光敏剂.
Properties of four indoline dyes were studied by means of density functional theory （DFT） and timedependent density functional theory （TD-DFT） with the goal of finding an excellent photosensitizer for use in dyesensitized solar cells. Theoretical results showed that the frontier molecular orbital structures of indoline dyes are suitable for electron injection from the excited states of indoline dyes to a TiO2 electrode. Calculated UV-visible absorption spectra of indoline dyes in vacuum match well with solar radiation spectra. The calculated energy levels of these dye molecules demonstrate that indoline dyes can be used as photosensitizers for TiO2 nanocrystalline solar cells together with the I^-/I3^- electrolyte. The lowest unoccupied molecular orbital （LUMO） energy levels of indoline dyes are higher than the conduction band edge of the TiO2 crystal, which ensures a high efficiency of electron transfer from indoline dyes to TiO2 electrodes. As the highest occupied molecular orbital （HOMO） energy levels of indoline dyes are lower than those of I^-/I3^-, molecules that donated electrons can receive electrons from the electrolyte. By comparison with the experimental data, the transfer efficiency of dye-sensitized solar cells may be determined mainly by the LUMO energy levels. The working lifetime of a dye-sensitized solar cell depends mainly on the stability of the dye molecule. From an analysis of the bond length of chemical bonds, we find that the stability of the four indoline dye molecules is basically the same. We further show that indoline dye 1 （ID1） has the highest LUMO energy level and the highest molecular stability. Its absorption spectra match solar radiation spectra well in an ethanol solution, therefore, itis the best photosensitizer among the analyzed dyes for application in dye-sensitized solar cells.
出处
《物理化学学报》
SCIE
CAS
CSCD
北大核心
2009年第10期2087-2092,共6页
Acta Physico-Chimica Sinica
