Effect Of Organic Functional Materials On Perovskite Hole Transport Layer

With the growing energy demand and the rapid development of the photovoltaic industry,perovskite solar cells with excellent photovoltaic performance have attracted much attention due to their high photoelectric conversion efficiency.However,perovskite prepared by the solution method suffers from problems such as difficulty to control crystal growth and more defects on the surface of the film,leading to severe carrier complexation at the interface between it and the charge transport layer.All these problems are obstacles to research on perovskite solar cells.Therefore,the development of novel interfacial passivation materials and new small molecule materials as hole transport materials is important to obtain efficient and stable cell devices.To address these issues,this thesis has designed and synthesized three organic small molecule functional materials containing triphenylamine groups to improve and optimize the performance of perovskite solar photovoltaic devices.The details are as follows.（1）Based on the excellent properties of triphenylamine groups,organic small molecules containing phosphonic acid groups（TPA-P）were designed and synthesized for application in orthotropic FAPb I₃ perovskite solar cells as interfacial modification materials.The results show that the interaction between TPA-P and Pb²⁺effectively passivates the surface defects of the FAPb I₃ film and reduces the non-radiative compound,thus improving the quality of the perovskite film and accelerating the charge transfer from the perovskite layer to the hole transport layer.Through the optimization of TPA-P,the prepared perovskite solar cells achieved a photovoltaic conversion efficiency（PCE）of 21.09%and showed good stability under humidity and heating conditions.（2）poly（triphenylamine）（PTAA）is a commonly used hole transport layer material,but the low carrier mobility of PTAA hinders device performance enhancement.Based on this,we designed and synthesized tapered covalent organic molecules（TPA-C）containing a cyclicΠ-conjugated,sp³-hybrid structure for application in the hole transport layer of MAPb I₃ inverted cells^[56].It was shown that compared to conventional hole transport materials,TPA-C not only possessed higher hole mobility but also promoted the growth of larger large grains in the perovskite films,thus improving the cell performance.（3）In addition,we also designed and synthesized organic materials（TPA-FC）based on TPA-C with fluorene units as new peripheral groups for application in MAPb I₃ inverted solar cells.It was shown that the deposited perovskite film had a larger grain size compared with the conventional hole transport material PTAA,which effectively passivated the surface defects of the perovskite film and showed better passivation and significantly reduced non-radiative compounding.The devices obtained 16.01%photoelectric conversion efficiency and showed good stability in the air environment.