Study On Spacer Layer In Mesoscopic Perovskite Solar Cells

In recent years,perovskite solar cells,a novel solar cell based on perovskite materials,has a rapid progress.The power conversion efficiency?PCE?has been greatly improved.And perovskite solar cells exhibit advantages of low cost,easily preparation process,flexible devices and large area can be prepared.The open circuit voltage(V_oc)of holeconductor-free carbon-based perovskite solar cells is low,which is closely related to the spacer layer between electron transport layer and counter electrode.The insulation will be not good and lead to serious charge recombination if spacer layer is too thin.And the carrier transmission distance will be too long to reduce recombination if spacer layer is too thick.So,V_oc and PCE can be reduced in above two cases.Therefore,developing a novel spacer structure is meaningful for the improvement of V_oc.In this thesis,we designed and applied two new types of spacer structures in holeconductor-free carbon-based perovskite solar cells,which could reduce the recombination of internal electron-hole pairs under the condition of thin spacer layer,and greatly improved V_oc and PCE.One is the insertion of a bifunctional Al₂O₃ layer between TiO₂ and ZrO₂.We found that the presence of Al₂O₃ interlayer not only serves as an excellent insulating layer with ZrO₂ to separate the TiO₂ and carbon electrodes but also modifies the interface between TiO₂ and perovskite when part of Al₂O₃ fell inside the pores of TiO₂ film,which further inhibited the recombination at electron transport material/counter electrode and the interfaces of electron transport material/perovskite at one time.As a result,the V_oc raised from 836 to 942 mV and achieved the highest PCE of 14.26%.And we designed a shelltype inverse opal Al₂O₃ spacer layer.The interconnected porous structure can not only achieve good filling of the perovskite,but also facilitate the transfer of charge.And good insulating property with thin films can reduce the recombination between electron transport material and counter electrode.As a result,the V_oc raised from 781 to 903 mV and achieved the highest PCE of 13.06%.