Effect Of Regulating Metal Oxide Interface Layer On The Performance Of Polymer Solar Cells

Organic polymer solar cells are lightweight,flexible,inexpensive to fabricate,suitable for solution processing and have a low impact on the environment.So they have attracted attention because of its potential in flexible wearables,PV building integration,etc.A disadvantage of current polymer solar cells is the low power conversion efficiency.Interface engineering is an effective approach to enhance the power conversion efficiency.The development of interfacial materials with appropriate charge selection capability and energy level matched to the active layer material is important to further improve the efficiency and stability of organic polymer solar cells.For this purpose,a typical metal oxide,ZnO,was selected as an interfacial material in organic polymer solar cells in this dissertation.Further optimization of the ZnO fabrication process resulted in higher power conversion efficiency of the devices.The main works are as follows.?1?The effect of doping PFN,an organic electron transport material,on the power conversion efficiency of polymer solar cell devices by modification of ZnO precursor solution was investigated.The results showed that the average power conversion efficiency of the device was highest at 8.71%when 0.4%PFN was doped into the ZnO precursor solution.Meanwhile,the effect of the temperature of sol-gel reaction in ZnO precursor solution on the optical properties of the solution and the power conversion efficiency of the corresponding polymer solar cell device was also studied.The results show that the power conversion efficiency of the polymer solar cell device corresponding to the ZnO electron transport layer prepared by the ZnO precursor solution with 15 ^oC sol-gel reaction temperature is the best,with a value of 9.05%.Combined with the optical characterization of the relevant solution,it was found that changes in solution temperature can adjust the band gap and defect distribution of ZnO and reduce the recombination loss between holes and electrons at the interface.?2?The effect of nanoscale size and distribution of colloidal particles in ZnO precursor colloidal solutions on the photovoltaic properties of the ZnO interface layer and the performance of polymer solar cells was investigated by controlling the colloidal particle size during colloidal ageing.The results show that the ZnO film prepared by the2 h aged precursor colloidal solution has a good crystal structure and surface morphology,which can facilitate the electron transfer between the active layer and the ZnO electron transport layer.Using this ZnO film as the electron transport layer of the PTB7-Th:PC₇₁BM photovoltaic system resulted in a maximum power conversion efficiency of 10.21%.The combination of the optical characterization of the functional layers and the electrical properties of the device shows that the higher power conversion efficiency of the polymer solar cell device is mainly due to the changes in the crystal structure and surface morphology of the ZnO thin film,which leads to a lower recombination probability of holes and electrons at the interface in the device,ultimately leading to a decrease in photocurrent.In summary,this study shows that the adjustment of sol-gel preparation process and doping of organic electron transport material PFN can effectively improve the power conversion efficiency of polymer solar cell devices and lay a solid foundation for the future commercialization of polymer solar cells.