Research On Improving The Performance Of Perovskite Solar Cells By Additive Engineering

With the rapid development of global science and technology,the urgent need for renewable energy in human society drives the continuous generation of solar cells.Perovskite solar cells（PSCs）stand out with their excellent performance and rapid development speed among the third-generation thin film solar cells and become one of the hot spots in the energy field.However,there are various defects in perovskite and transport layer films,and PSCs are faced with serious stability problems.These factors still restrict the development of PSCs to commercialization.Therefore,the use of effective additives to passivate the defects in PSCs,reduce the loss of carriers,and improve the quality of films is a key strategy for the fabrication of efficient and stable PSCs.In this thesis,the fabrication of high-performance PSCs is the research goal.Additive engineering was used to regulate the surface defects of perovskite films,the defects of hole transport layer（HTL）and electron transport layer（ETL）,and the defects in perovskite bodies,which improved the efficiency and stability effectively and achieved high-performance PSCs.The specific research contents are as follows:（1）The rare-earth-based quantum dots Cs₃Tb Cl₆ were synthesized by the improved hot injection method and introduced into the surface of perovskite film.Through the solid-state diffusion process,the Pb vacancy defects on the surface of perovskite film were successfully passivated,the defect state density in the perovskite film was reduced,the interface carrier recombination was inhibited,and the film quality was improved.At the same time,Cs₃Tb Cl₆ quantum dots can regulate the energy level matching and effectively prevent the transport of O₂ and H₂O from the hole transport layer（HTL）to the perovskite layer and other functional layers,thereby improving the efficiency and stability of PSCs.The Cs₃Tb Cl₆ quantum dots-modified device achieves a champion power conversion efficiency（PCE）of 22.89%and an ultra-high open-circuit voltage(V_oc)of 1.235V.The modified device improves the humidity stability and long-term stability effectively.（2）Black phosphorus quantum dots（BPQDs）synthesized by ultrasonic stripping were introduced into hole transport layer Spiro-OMe TAD as dopants to optimize the photoelectric performance of HTL.The introduction of BPQDs improves the Spiro-OMe TAD conductivity and carrier mobility,inhibits the carrier recombination at the interface,improves the carrier transport efficiency,and thus improves the performance of PSCs.Finally,the PSCs prepared by doping Spiro-OMe TAD with BPQDs obtained the optimal PCE of 23.49%and the filling factor was 80.32%.（3）Three transition metal carbide（MXene）materials（Nb₂CT_x-MXene,Ti₃C₂T_x-MXene,and V₂CT_x-MXene）were synthesized by HF wet etching and TMAOH stripping,and then introduced into the surface of Sn O₂ layer through interface engineering to fabricate PSCs.It was found that Nb₂CT_x-MXene showed better potential.The introduction of Nb₂CT_x-MXene can reduce the density of defect states on the surface of Sn O₂ film effectively,and regulate the energy level position while improving the conductivity of Sn O₂ film.Subsequently,Nb₂CT_x-MXene was loaded with Au NPs based on optical regulation engineering.Au@Nb₂CT_x-MXene composites have the ability to improve the quality of perovskite film,regulate the tensile strain during the growth of perovskite,and suppress the Auger recombination.Au@Nb₂CT_x-MXene modified device achieves an optimal PCE of 23.78%and a high V_oc of 1.215V.At the same time,the modified devices show greatly improved light stability,humidity stability,and operation stability.（4）The amphiphilic biomolecular additive astaxanthin（ASTA）was introduced into FAPb I₃-based PSCs as an organic additive to achieve the regulation of defects in perovskite.ASTA can reduce the defect activation energy of perovskite films,regulate deep-level defects by filling the grain boundaries（GBs）,and promote the crystallization ofα-phase perovskite effectively.The first-principle calculation results show that ASTA has a large dipole moment of 1.85 debye,which has the ability to promote carrier transport,and its unique groups can strongly interact with the uncoordinated Pb²⁺.More importantly,the ASTA-modified PSCs have a quasi-Fermi level splitting（QFLS）of1.164 e V and a V_oc loss of only 96 m V,and the ASTA-modified PSCs have a PCE of up to 24.56%.At the same time,the introduction of ASTA improves the humidity stability,oxygen stability,and long-term stability of PSCs significantly.Finally,in order to meet the needs of the practical application of large-area PSCs,PSCs fabricated with an effective area of 1.002 cm² obtain a PCE of 22.41%and have excellent performance in the application of electrolytic water to produce hydrogen energy,thus accelerating the process of PSCs to practical application.