Study On The Performance Of Perovskite Solar Cells Based On Oxide Charge Transport Layers

Perovskite solar cells?PSCs?have developed rapidly in recent years.Solution and vapor-solid methods are two commonly used methods for preparing perovskite films in the laboratory.In this thesis,we prepared high-quality methylammonium lead iodine?MAPbI₃?thin films using the vapor-solid method.Then we prepared two different types of oxide films?NiO and TiO₂?,on which planar-structure PSCs were prepared and their performances were compared.Main contents of the thesis are as follows.We first studied how to prepare high-quality perovskite films.We monitored the growth of perovskite with in-situ resistance and compared properties of perovskite films at different reaction times.Meanwhile,to facilitate the diffusion of MAI into PbI₂ films,we prepared porous PbI₂ films using H₂O or DMSO as an additive of the PbI₂ precursor solution.Finally,we prepared p-i-n devices with a structure of ITO/PEDOT:PSS/MAPbI₃/PCBM/BCP/Ag,which exhibits a power conversion efficiency?PCE?of 12%without hysteresis.Then,we prepared NiO films with a sol-gel method and used them as hole transport layers of inverted PSCs that had a structure of ITO/NiO/MAPbI₃/PCBM/BCP/Ag.To improve the conductivity of the NiO films,we doped them with different amounts of Li⁺,Mg²⁺and Cu²⁺.We analyzed the samples with XRD,EDS,AFM and XPS.The results show that the composition of each NiO film is the same as the corresponding precursor.The NiO films show smooth surfaces,which could facilitate the interfacial charge transfer.Devices based on LiNiO?NiO doped with 15%Li⁺?films showed an efficiency of 16%with negligible hysteresis.A large-area?1.0 cm²?invert-structure device was fabricated on the LiNiO film,and showed an efficiency of 13%.Finally,we prepared TiO₂ films with a sol-gel method,and used them as the electron transport layers of normal-structure PSCs?FTO/TiO₂/MAPbI₃/PTAA/Ag?.By optimizing the thickness of the TiO₂ films,the device efficiency reached 16%,with insignificant hysteresis.A large-area?1.0 cm²?normal-structure device was also fabricated,which showed an efficiency of 13%.We further compared the light stability,UV stability,thermal stability and air stability of the two types of PSCs.The results show that the normal-structure PSCs based on TiO₂ have better light stability and thermal stability,while the NiO-based invert-structure PSCs have better UV stability and air stability.