Study On The Photoelectric Performances Of Perovskite Solar Cells Based On Multifunctional Additives And Interface Engineering

In recent years,solar cells with a light-absorbing layer of ABX₃ hybrid metal halide perovskite have been developing rapidly.Up to now,its power conversion efficiency（PCE）has exceeded 25%,which shows great potential to become the core photovoltaic technology in the future.However,the PCE and operational stability of both regular-structure（n-i-p）and inverted-structure（p-i-n）perovskite solar cells（PSCs）have been severely limited by the insufficient charge transport with unresolved carrier dynamic mechanism issues,as well as interfacial energy barriers caused by trap-assisted non-radiative recombination at grain boundary and the internal contact surface of the functional layers.So far,most efforts based on solution to interfacial defects at a monolayer have been made to improve PSCs performance.However,there is still a lack of universal approaches for the industrialization of PSCs to adjust the photoelectric properties of multi thin films including both perovskite and charge transport layers.To solve the above problems,this thesis mainly focuses on interface energy level alignment,simultaneous bulk/surface defect passivation,and promotion of the key materials grow orientation,and combine with the interface engineering based on multifunctional additives to collaboratively adjust the light-absorbing layer and the charge transport layer with their contact interface,so as to comprehensively deal with the main bottlenecks of the PSC commercialization.The main work is summarized as follows.（1）Based on the different characteristics of the p-i-n and n-i-p structures,device structure in the thesis has been determined first.By investigating the effect of the BCP buffer layer,the application of different hole transfer materials in p-i-n structure,the effect of perovskite layer film quality on device performance of both the p-i-n and n-i-p structures,the optimum preparation technique was explored.The optimized device achieves a PCE of 17.78%（n-i-p）and 17.86%（p-i-n）,respectively.As a result,the devices based on the p-i-n structure exhibit lower hysteresis,higher efficiency and enhanced stability.（2）Triiodide anion（I₃^-）was used as passivation ligand to optimize the interface contact between the perovskite layer and hole transport layer for improvement of the preferential orientation of perovskite crystals,and explore its application to the p-i-n structure and n-i-p structure.The results show that I₃^-can strongly interact with iodine vacancy and undercoordinated cation in perovskite and form an ultrathin passivation layer at the interface between the hole transport layer and the perovskite layer,which can effectively improve the quality of the perovskite film,reduce the interface non-radiation recombination,and enhance the interface charge transfer ability,and finally get improvement of the performance of both structures devices.Finally,a champion PCE of 18.87%was obtained at the concentration of 4%for the n-i-p structure,and19.57%efficiency was obtained at 6%in the p-i-n structure.（3）The 4-chloromethylbenzonitron（CBN）multifunctional additive is used to synergistically treat both the hole transport layer and the electron transport layer.With a single additive,the internal defects of p-i-n structure devices are fully passivated,the energy level alignment between the different functional layers is improved,and the p-i-n devices with high stability are obtained.Ultimately,the device efficiency increased from 18.87%to 20.2%with a device efficiency retention of 80%after 1000 hours.