Research On Optical Simulation And Optimization Of Organic Photovoltaic Devices

Organic photovoltaic（OPV）cells achieve photoelectric conversion through the absorption of photons by organic materials,and have been considered as one of new energy source for lighting,construction,communication and other fields due to its distinct advantages such as lightweight,low cost,good mechanical flexibility and adjustable absorption band.However,the relatively low power conversion efficiency（PCE）of OPVs restricts their widespread application and promotion.Therefore,exploring effective ways to improve the efficiency of OPVs is a current research hotspot.Optical modeling and optimizaiton method,which can predict the device performance and avoid tedious trial-and-error processes and help researchers to explore and understand the internal mechanisms of device,has become an indispensable tool in optical design and optimization process of OPVs.However,the diversification of OPVs’structures and application scenarios impose greater demands on the optical modeling theory and optimization strategy.Existing optical models suffer from problems such as neglecting optical anisotropy and difficulty in dealing with nanostructures quickly and accurately.Besides,in the design process of OPV cells based on optical models,only the short-circuit current density(J_SC)at normal incidence is optimised,and the actual working conditions and processing windows are not taken into account.In view of this,this dissertation will carry out the research on the optical modeling of OPVs and its application from the following aspects:An optical modeling method for OPV device considering the optical anisotropy is proposed.Based on the 4×4 matrix method,the transmission coefficient of substrate is introduced to modify the coherent simulation results obtained by 4×4 matrix method,then the optical model for stratified OPV devices considering optical anisotropy and coherent-incoherent hybrid multilayers is constructed.Furthermore,the expressions of performance parameters of OPV devices are derived.Using the proposed method,the prediction and analysis of the device performance and power distribution can be realized.An optical modeling method for nano-structured OPV is developed.Via combining the rigrous coupled wave analysis method（RCWA）and bidirectional scattering distribution functions（BSDF）,the angular distribution transmission coefficient is deduced to correct the coherent simulation results.Then the accurate simulation of the coherent-incoherent hybrid OPV device with periodic nanostructures are realized.In addition,the analysis and optimization based on the proposed method are carried on the single and tandem OPV with nanostructures,respectively,which shows the potential of the method in the mechanism research and structure design.A robust design strategy for OPV considering the process window is proposed to design the industrialized OPVs in different application scenarios.A screening method for the variables which have significant effect on the device performance is proposed.Further,via combining the performance fluctuation loss and the tolerance control cost,the total cost function is constructed to introduce the tolerance into the design process,and then the geometrical parameters and tolerances for devices are designed simultaneously.Finally,the geometrical parameters and tolerances of a semi-transparent OPV used as architectural glass coating are designed.The device performance is robust and excellent,and the device qualification rate is significantly higher than that of devices designed without the introduction of tolerances at the same process level.The optical optimization experiment of tandem OPV under variable incident conditions are carried out.Considering the continuous change of the incident angle,the energy density generated during the whole working period is taken as the optimization target,which significantly improves the comprehensive performance of OPV during the whole working period.Based on the proposed method,a typical tandem OPV is optimized and prepared,the experiments results show that the energy density generated per day of the device optimized considering the variable incident angle during daytime is increased by 5%compared to the device that only consider normal incidence condition.The series methods proposed in this dissertation provide efficient solutions for the optical simulation and analysis of stratified OPV,and novel theories for optimization of OPV devices in practice,which are expected to promote the development of the OPV industry.