Theoretical Computation And Molecular Design On Porphyrin Sensitizers And Hole Transport Materials

Solar cells have attracted much interest due to the energy crisis.This research investigated the key of Dye sensitized solar cells,sensitizers,and the the key of Perovskite solar cells,hole transport materials,from the prospects of theoretical computation and molecular design.This research was based on the Density Functional Theory,and adopted Gaussian 09 software and Multiwfn software.On the one hand,it explained the experimental results by theoretical computation and explored the relationships between structures and properties.On the other hand,it verified the foundings by strategic molecular design and screened out the potential candidates for synthesis in the future.Our studies on porphyrin sensitizers showed that stronger donors would be favorable for the charge transfer and boost the cell performance,but extremely strong donors would lead that the HOMO of dyes lied higher than the redox potential of the redox couple?I^-/I₃^-?,therefore the oxidized dyes couldn't be regenerated and closed circuit couldn't be generated.As the length of alkyl chains increased,the energy levels would not be changed.But proper length of alkyl chains would facilitate effective charge transfer excitation and boost the photocurrent density measured at short circuit.When the LUMO lied quite low,the open-circuit voltage would decrease dramatically,which lead to the cell performance fall sharply.Three new designed “D-?-A type” porphyrins LP-2?which had tetraphenylporphyrin as donor,benzo-2,1,3-thiadiazole and ethylene at ? position as ? spacer,and carboxyl as acceptor?,LP-4?which had tetraphenylporphyrin as donor,alkynyl and benzo-2,1,3-thiadiazole and ethylene at ? position as ? spacer,and carboxyl as acceptor?,LP-8?which had triphenylporphyrin as donor,Benzo-2,1,3-thiadiazole and ethylene at meso position as ? spacer,and carboxyl as acceptor?had the potential for efficient sensitizers.Our studies on hole transport materials showed that new designed dyes molecule-4^molecule-7?which had divinyl or divinyl-dithienyl-divinyl or trithienyl as the core units terminated with triphenyamine derivative??molecule-8^molecule-10?which had pyrene as the core unit terminated with one or two or four dithienyldiphenylamine substituents??molecule-12?which had pyrene–dithienyl-pyrene as the core unit terminated with four diphenylamine substituents?had suitable alignment of energy levels,so they had passed the screening.It boosted the HOMO level but increased the reorganization energy when replaced phenyl with thiophene,or adding more ethylene/diarylamine substitutes,or adding less pyrene.In this dissertation,it is the first time that extended condensed Fukui Function was adopted to describe the electron donating abilities accurately in a quantitative level and Tangui Le Bahers' model was applied to study the charge transfer process of porphyrin sensitizers.The studies gave good reasonable explainations to the experimental results of porphyrin sensitizers from the prospects of electronic stuctures and electronic properties.In addition,it also guided the studies on structure-property relationships,molecular design and synthsis.