Research On Wide Band Gap Formamidine Lead Halide Perovskite And Related Tandem Solar Cells

In recent years,tandem solar cells（TSCs）based on wide-bandgap（WBG）perovskite materials have been the focus of research.However,WBG perovskite materials have some problems to be solved due to its unique properties such as photobiological phase separation.Based on the analysis of the existing problems of the WBG perovskite materials,this dissertation aims to improve the performance and stability of the WBG perovskite solar cells（PSCs）.Starting from the selection of the transport layer,the effects of different hole transport layer materials on the performance of the WBG perovskite devices are analyzed and compared.Secondly,multi-functional additives are used to improve the WBG perovskite solar cells.Then the perovskite-transport layer interface was further optimized.Finally,the preparation process of high-efficiency semitransparent PSCs and their TSCs is deeply studied,which contributes to the development of PSCs.The primary research topics addressed in this work are as follows:（1）The effect of molecular weight of polymer materials on the performance of inverted perovskite solar cells is systematically studied.An efficiency of 19.24%was obtained in the inverted device.At the same time,the performance differences of different hole transport layer materials in the WBG perovskite devices are analyzed and compared,which lays a foundation for the preparation of high-performance broadband gap PSCs.（2）Antimony potassium tartrate（APTA）was used is introduced into WBG perovskite precursor as a multifunctional additive.The results show that the addition of APTA can improve the quality of the perovskite film and inhibit the phase separation of the film.At the same time,APTA can improve the film stability by coordinating with unbonded lead in perovskite,and can change the band structure of perovskite to improve the charge transport performance at the interface.The defect analysis of WBG perovskites shows that APTA can reduce the energy level of defect states,significantly reduce the density of defect states,and promote the carrier transport and reduce recombination.Finally,an efficiency of 20.35%was obtained based on the APTA-assisted WBG PSC.At the same time,the stability of PSC has also been improved,maintaining 80%of their initial efficiency after 1000 hours of continuous operation under a standard sunlight.（3）Halide material 1,3-prophaiediamine dihydriodide（PDAI₂）was used to passivate the WBG perovskite surface.It is found that PDAI₂ materials can not only change the surface morphology of perovskites and improve the surface potential distribution of WBG perovskites,but also increase the carrier lifetime of perovskites and reduce defects,thereby increasing the open circuit voltage of devices.Finally,based on the surface modification of PDAI₂,we obtained a photoelectric conversion efficiency of 21.48%in the 1.68 e V bandgap WBG perovskite device with an open circuit voltage of 1.243 V.To a certain extent,the open voltage loss was greatly reduced and the stability of the device is also improved.（4）The electrode preparation process of semitransparent PSC was systematically studied.ITO transparent electrodes with an average transmission rate of more than 80%were fabricated,and high-performance transparent electrode materials were utilized to prepare semi-transparent perovskite solar cells with an efficiency of over 20%.An all-perovskite four-terminal TSC with an efficiency of 26.3%was prepared by combining a WBG semitransparent cell with a narrow-band gap tin perovskite cell.At the same time,a four-terminal perovskite/CIGS tandem cell with an efficiency of 27.2%was obtained.Finally,perovskite/silicon TSCs with efficiency over 26%were also fabricated.