The Development Of Highly Efficient Inverted Planar Heterojunction Perovskite Solar Cell

Perovskite solar cells（PSCs）have attracted more and more attention because of their high photoelectric conversion efficiency（PCE）,high carrier mobility,long carrier diffusion length and easy fabrication technique.At present,the hot research topics of perovskite solar cells include improving solar cell efficiency,interface engineering,long-time stability,lead-free perovskite solar cell,and all-inorganic perovskite solar cell.In this thesis,highly-efficient inverted planar heterojunction perovskite solar cells were obtained by interface modification and surface passivation due to the modified interface of perovskite crystals.The specific work of this paper can be divided into the following three parts:（1）Edible materials glycerol and choline chloride were used as the interface materials between NiO_x and NH₃CH₃PbI₃（MAPbI₃）.MAPbI₃ film fabricated on the modified NiO_x has smoother surface and more uniform grains,leading to an enhancement of PCE from 13.37%to 15.25%because of the increased J_SC from 17.77 to 20.35 mA/cm².The mechanism investigation suggested that the enhancement of surface wet ability of NiO_x after glycerol and choline chloride modification play an important role in the morphology improvement of MAPbI₃ film.This work provides a new and more environmentally friendly choice for interface modification.（2）A single molecule buffer layer is formed by spin-coating GO deionized water dispersion on the surface of the NiO_x film.There were two factors explaining the influence of GO single-molecular buffer layer on NiO_x.On the one hand,graphene oxide has good hydrophobicity,which can effectively block the penetration of water and avoid the accelerated decomposition of perovskite.On the other hand,perovskite crystal of good quality can be obtained after modification of NiO_x,leading to the enhancement of V_OC and J_SC.It was found 0.05 mg/mL was the optimal concentration of GO in deionized water inconsideration of the efficiency of perovskite solar cell.The PCE of champion device enhanced from 13.20%of the control device to 15.18%.The huge improvement of device performance can be attributed to the larger hole mobility,lower leakage current,reduced carrier recombination,and improved charge extraction efficiency than that of the control device.（3）The mixture of glycerol and choline chloride was deposited by spin-coating on the surface of perovskite film in order to passivate perovskite active layer.The influence of passivation on the performance of perovskite solar cell was investigated.Experimental results demonstrated that the performance of the device is improved after depositing choline chloride,while decreased after using glycerin for passivation.However,the best performance of device was achieved when using glycerin:choline chloride mixture for passivation.Compared with control device,the V_OC of the best modified device increased from 1.03 V to 1.06 V and the J_SC increased from 16.35 mA/cm² to 18.89 mA/cm²,leading to the increase of PCE from 13.22%to 15.02%.This work provides a simple process of surface passivation for the fabrication of efficient PSCs.