Research On The Interface Regulation And Performance Optimization Of Planar Perovskite Solar Cells

In recent years,organic-inorganic hybrid perovskite materials have been widely studied due to their long carrier lifetime,high optical absorption coefficient,adjustable band gap,low cost,and simple preparation process.The photoelectric conversion efficiency of the third generation solar cells based on hybrid perovskite materials has increased from 3.8%in 2009 to 25.7%currently,which is comparable to the first-generation silicon solar cells.However,there are many problems in hybrid perovskite solar cells,such as low intrinsic carrier concentration in the charge transport layer,low stability of perovskite materials,Li⁺migration accelerating the decomposition of perovskite,and serious hysteresis in devices,which greatly limit their commercial applications.In response to the above issues,this paper aims to improve the stability of perovskite solar cells as the main research objective,as well as take the transport layer and light absorption layer of perovskite solar cells as the main research content.The effects of the charge transport layer,light absorption layer,and the interface between them on perovskite devices’stability and photoelectric conversion efficiency have been systematically studied.The main research contents of this article are summarized as follows:1.The effect of Na₂WO₄ modified SnO₂ electron transport layer on perovskite devices’photovoltaic performance and stability was studied.The results show that Na₂WO₄ doping can effectively improve the conductivity of the SnO₂ electron transport layer and the energy level matching between the SnO₂ and perovskite,thereby improving the carrier extraction ability.The device based on the SnO₂-Na₂WO₄ electron transport layer achieves a photoelectric conversion efficiency of 21.16%,increasing by 22%compared to the original device.Moreover,the optimized device also has better humidity and thermal stability.After exposing the unpacked device to RT,85%RH,and 70℃,70%RH for 1000 hours,it can maintain initial efficiency of 83.8%and 73.2%,respectively.2.The effect of introducing a Na₂S dual functional layer between SnO₂ and perovskite on the photovoltaic performance and stability of perovskite devices was studied.The results show that the S atom in Na₂S simultaneously compensates for the oxygen vacancies in SnO₂and the halogen vacancies in perovskite at the interface,thereby inhibiting the carrier recombination induced by interface defects.In addition,the interaction between the S atom and the electron transport layer and perovskite also improves the energy level matching between them,making electron transport from perovskite to the electron transport layer more efficient.The device based on the SnO₂/Na₂S charge transport layer achieved an efficiency of 21.21%,increasing by 23%compared to the original device.Moreover,the fixation effect of S atoms on the Pb-I octahedral framework also improves the humidity and thermal stability of perovskite devices.3.The effect of cellulose acetate butyrate（CAB）on the performance of perovskite films and perovskite devices was studied.The results showed that the introduction of CAB improved the crystallinity of perovskite films,decreased the defect density of perovskite films,and improved the energy level matching between perovskite films and hole transport layers.As a result,the optimized device achieved an efficiency of 21.5%,which was about18%higher than the original device.Furthermore,the bonding between functional groups in CAB and ions in perovskite also enhances the resistance of perovskite to heat,humidity,and ultraviolet light.The target device can maintain 90.1%and 92.3%of its initial efficiency after aging under high heat,high humidity,and continuous light conditions for 500 hours,respectively.4.The effect of introducing the MOF interface layer between perovskite and Spiro-OMe TAD hole transport layers on the photovoltaic performance and stability of perovskite devices was studied.The results show that MOF can bond with Pb and organic cations on the surface of perovskite,thereby passivating perovskite surface defects.Finally,the device based on Cr-MOF achieved an efficiency of 21.71%,which is about 14%higher than the original device.Furthermore,since the MOF interface layer can block Li⁺migration and inhibit the invasion of water molecules into perovskite,the environmental stability of perovskite films is significantly improved.The unpacked device can still maintain more than 91%of the initial efficiency after aging at RT and 40%RH for 2500 hours,while the original device can only maintain about 55%of the initial efficiency.5.The effect of 1-hexylimidazole（HD）replacing 4-tert-butylpyridine（t BP）on the performance of Spiro-OMe TAD transport layers and perovskite devices was studied.The results show that the doping of HD improves the surface morphology of Spiro-OMe TAD,thereby improving the interface contact with perovskite and counter electrode.In addition,the electrical properties and energy level structure of Spiro-OMe TAD have also been improved.The device based on Spiro-HD achieved an efficiency of 21.53%,which is 11%higher than the control device.Furthermore,the long-term stability of perovskite films has also been improved due to the doping of HD inhibiting the formation of holes in the hole transport layer.The optimized device can still retain an initial efficiency of 93%after aging for 1000 hours at RT and 50%RH,while the original device only retains about 81%of the initial efficiency.