CAJ | 학술논문

为了揭示D-SS和D-ST分子敏化的染料敏化太阳能电池(DSSCs)的物理机制,采用密度泛函理论(DFT)、含时密度泛函理论(TDDFT)和自然键轨道(NBO)分析,模拟计算染料D-SS和D-ST分子的结构、紫外-可见吸收光谱和能级结构.D-SS的紫外-可见吸收光谱相比于D-ST的有明显的红移,而且D-SS分子的摩尔吸光系数也高于D-ST分子的.D-SS分子本应该比D-ST分子拥有更高的俘获太阳辐射光子的能力,但由于D-SS分子的最高占据分子轨道(HOMO)能级位置比氧化还原电解质(|-/|-3)的氧化还原能级高,处于光激发态的D-SS分子向TiO2电极注入电子而被氧化后,不能顺利地从电解质中得到电子而还原,使得D-SS分子俘获光子的能力不能充分发挥,从而严重地降低了由其敏化的DSSCs的光电性能和光电能量转换效率.揭示了D-SS敏化的DSSCs的光电性能,特别是光电能量转换效率比D-ST敏化的DSSCs的低的原因.染料敏化剂分子的HOMO能级的位置对于DSSCs来说也是很重要的,用于DSSCs的有机敏化剂分子的HOMO能级的位置必须低于氧化还原电解质的氧化还原能级.
위료게시D-SS화D-ST분자민화적염료민화태양능전지(DSSCs)적물리궤제,채용밀도범함이론(DFT)、함시밀도범함이론(TDDFT)화자연건궤도(NBO)분석,모의계산염료D-SS화D-ST분자적결구、자외-가견흡수광보화능급결구.D-SS적자외-가견흡수광보상비우D-ST적유명현적홍이,이차D-SS분자적마이흡광계수야고우D-ST분자적.D-SS분자본응해비D-ST분자옹유경고적부획태양복사광자적능력,단유우D-SS분자적최고점거분자궤도(HOMO)능급위치비양화환원전해질(|-/|-3)적양화환원능급고,처우광격발태적D-SS분자향TiO2전겁주입전자이피양화후,불능순리지종전해질중득도전자이환원,사득D-SS분자부획광자적능력불능충분발휘,종이엄중지강저료유기민화적DSSCs적광전성능화광전능량전환효솔.게시료D-SS민화적DSSCs적광전성능,특별시광전능량전환효솔비D-ST민화적DSSCs적저적원인.염료민화제분자적HOMO능급적위치대우DSSCs래설야시흔중요적,용우DSSCs적유궤민화제분자적HOMO능급적위치필수저우양화환원전해질적양화환원능급.
The molecular structures,UV-Vis absorption spectra,and energy level structures of the dyes D-SS and D-ST were simulated using density functional theory,time-dependent density functional theory (TDDFT),and natural bond orbital analysis,which provided the physical mechanisms of dye-sensitized solar cells (DSSCs) containing D-ST and D-SS.The UV-Vis absorption spectrum of D-SS showed a significant red shift compared with that of D-ST and the molar absorption coefficient of D-SS was higher than that of D-ST.D-SS molecules should have a higher solar radiation photon-harvesting ability than D-ST molecules,but the energy level of the highest occupied molecular orbital (HOMO) of D-SS was higher than the redox energy level of the electrolyte (|-/|-3).As a result,an optically excited D-SS molecule cannot be successfully recovered by accepting an electron from the electrolyte after being oxidized by injecting an electron towards the TiO2 electrode.This limits the photon harvesting ability of D-SS molecules,and thereby significantly decreases the photovoltaic properties and energy conversion efficiency of DSSCs containing D-SS.This allows the photovoltaic properties of DSSCs containing D-SS to be understood,especially why its photovoltaic energy conversion efficiency is lower than that of DSSCs containing D-ST.The position of the HOMO energy level of dye-sensitized molecules is very important for the operation of DSSCs,and that of the organic sensitizer molecules used in DSSCs must be lower than the redox energy level of the electrolyte.