Study On The Interface Modification And Charge Transfer Exciton Of Organic Solar Cell

Organic solar cells (OSCs), which are on behalf of the third generation ofphotovoltaic devices, have shown great potential due to the advantages of low-cost,light weight, wide sources, low energy consumption and large-scale production.Researchers from around the world have done a lot of investigationsto make the powerconversion efficiency of the organic solar cell meet the practical standards. In order toimprove the efficiency of organic solar cell, the main work of this paper is to study theinfluence of cathode buffer layers, thermal annealing, solvent additive and dye dopingon the performance of the devices. Thus, this paper includes three parts:1. Study the influence of cathode buffer layers on the planar heterojunction smallmolecular inverted OSCs. In this paper, several commonly used electron transportmaterials were applied in small molecular inverted solar cells as cathode buffer layer.The LUMO level and electron mobility of these materials were compared toinvestigate their influence on the device performance. In addition, the DLC material,HATNA, was firstly used as cathode buffer layer, and its device characteristics werecarried out. Lastly, through simulating J-V curve based on SCLC theory, theorganic/electrode interface barrier was reduced by27%through inserting the HATNA.2. Study the influence of thermal annealing and solvent additive on theperformance of small molecular bulk-heterojunction solar cells based on squaraine.Firstly, the optimized temperature of thermal annealing and optimized ratio of solventadditive were investigated. Then through the researches about the film morphology andcharge carrier mobility, the influences of thermal annealing and solvent additive on theorganic film were explained. Finally, the simulation on the photocurrent-voltagerelation based on Onsager-Braun theory showed that thermal annealing and solventadditive can enhance the CT exciton dissociation, improve the generation of chargecarriers so that the PCE was increased.3. Study the influence of ternary blend system by adding dye molecule on thepolymer bulk-heterojunction solar cells. In this part, the ternary blend system wasconstructed through doping small ratio of dye molecule, Rubrene, in P3HT:PCBMbulk-heterojunction solar cells. The performance of the devices withdifferent doping ratio was investigated. The results showed that by doping3.5wt%Rubrene, the JSCand PCE were increased by23.1%and23.4%, respectively. TheUV-vis absorption spectra indicated Rubrene can improve the absorption of the organicfilm from400nm to550. The simulation on the photocurrent revealed dye doping canenhance the CT dissociation, so the JSCof OSCs was increased.