Study On The Effect Of Functional Layer Regulation On The Performance Of Perovskite Photovoltaic Devices

Perovskite photovoltaic devices（Pe PVD）have been widely studied due to their excellent performance and unique advantages in large-scale,low-cost manufacturing.According to its application scenarios,Pe PVD can be divided into two categories:perovskite solar cell（Pe SC）and perovskite photodetector（Pe PD）.The main research direction of this dissertation is the functional layer regulation method of Pe PVD.Through thin film doping,interface modification and process optimization,this dissertation studies the impact of functional layer regulation on the performance of Pe PVD.This dissertation is divided into the following three parts::1.The effect of quantum dot material doping of photoactive layer on the performance of Pe SCBy doping different quantum dots（QDs）materials into the perovskite active layer,the film-forming quality of the active layer is regulated to enhance the device performance.Firstly,the inorganic perovskite quantum dot material CsPbI₃ QDs was doped into the MAPb I₃ film.On the one hand,CsPbI₃ QDs was utilized as the nucleation centers to enhance the film-forming densities of the active layer.On the other hand,the dissociated CsPbI₃ QDs were utilized to fill up the defects of the ionic vacancy,which enhanced the film quality of the active layer in terms of the ratio of the active layer elements and the crystallinity.Eventually,the active layer with high crystallinity and large grain size is realized,which reduces exciton recombination,improves carrier transfer,and enhances the device efficiency.The power conversion efficiency（PCE）of Pe SC is increased from14.85%to 17.04%,and the device performance degradation is much slower than that of the standard device.In addition,the metal oxide material In₂O₃ QDs is doped into the MAPb I₃ film to optimize the crystalline morphology and conductivity of the film,and to enhance the carrier dissociation and transport efficiency,which ultimately results in the optimized PCE,which is much higher than that of the undoped Pe SC.2.Effect of non-fullerene acceptor small molecule interfacial modification layer on the performance of Pe SCBy introducing a novel non-fullerene acceptor（NFA）material INDCDT-b8-Cl as an ultra-thin interfacial modified layer（IML）between the MAPb I₃ photoactive layer and the Phenyl-C61-butyric acid methyl ester（PCBM）electron transport layer,the performance of Pe SC was investigated.INDCDT-b8-Cl is enriched with a large number of Lewis group functionalities including carbonyl（C=O）and cyano（C≡N）groups.These functional groups help to form complexes with uncoordinated Pb²⁺or Pb clusters in the active layer,which is conducive to improving the interfacial defects in the photoactive layer and the carrier mobility in the transport layer,as well as to improving the exciton generation and dissociation and the carrier transport and injection processes,and to enhancing the carrier transport capability.As a result,the optimized Pe SC has excellent photovoltaic performance with a PCE of more than 20%.Under the same storage conditions,the optimized device based on NFA IML exhibits much higher stability than the control device.3.Effect of polyelectrolyte material doped electron transport layer on the performance of Pe PDThe performance of perovskite photodetectors is improved by introducing the polyelectrolyte material ethoxylated polyethylenimine（PEIE）into the PCBM electron transport layer of the Pe PD to construct a composite electron transport layer with excellent carrier transport capability and suitable energy levels.It is shown that a small amount of PEIE doping can not only improve the thin film morphology of the transport layer and optimize the carrier transport ability,but also effectively regulate the energy level of the electron transport layer and enhance the reverse injection barrier between the transport layer and the metal cathode.By establishing a carrier injection model at the semiconductor interface,the effect of the change of the reverse injection barrier on the photodetector dark current is investigated,and the mechanism of the significant decrease of the Pe PD dark current after optimization is revealed.Finally,the composite electron transport layer-based Pe PD achieved the highest specific detectivity of 4.77×10¹² Jones at 750 nm,which is much higher than that of control device of 1.57×10¹² Jones.In addition,the optimized Pe PD has a smoother light/dark response,better recovery characteristics and outstanding stability,which enhances the application and commercial potential of perovskite materials in photodetection field.4.Effect of solution-processed flexible polymer electrodes on the performance of Pe PDPoly（3,4-ethylenedioxythiophene）:poly（styrenesulfonate）PH1000（PH1000）,a polymer material prepared by the solution-processed method,was selected as the electrode material.And the electrode was modified by adding the additives ethylene glycol（EG）,4-dodecylbenzenesulfonic acid（DBSA）,（3-glycidyloxypropyl）trimethoxysilane（GOPS）to optimize the conductivity,flexibility and film uniformity of the PH1000 electrode.Based on this flexible electrode to construct a flexible perovskite photodetector device,the optimized Pe PD shows excellent bending resistance while maintaining high detection performance.After 2000 bends（curvature radius of 10 mm）,the normalized photocurrent can still reach 85%of the unbent device,which is much better than the standard device based on indium tin oxide（ITO）electrode（31%）,demonstrating excellent mechanical stability.In this dissertation,the application of functional materials and optimization strategies in regulating the functional layer of perovskite photovoltaic devices is investigated from different perspectives,and new ideas for optimizing perovskite photovoltaic devices are proposed,which provide a simple and efficient reference strategy for the industrial production and commercial promotion of perovskite photovoltaic devices.