Performance Optimization And Research Based On The Perovskite Solar Cells Under Ultraviolet Illumination

The organic-inganic hybrid perovskite material has a unique advantage of high extinction coefficient,long carrier diffusion length,controllable band,simple synthesis,low cost,etc.,and the photoelectric conversion efficiency(PCE)of the perovskite-based solar cell(PSC)using the novel light absorbing material reached a high record of 23.7%.At present,all third-party verified high-efficiency PSCs use Ti O2 as a dense layer or a naoporous carrier layer.Numerous studies have shown that the ultraviolet component of sunlight can decompose the perovskite material in such PSC,resulting in a decrease in the photostbility of PSC.However,there are also studies indicate the certain PV performance of PSC wil increase under certain ultraviolet light exposure,but the most critical PCE of the PSC still has not improved.In order to solve the above problems,this paper proposes a new UV-inducing strategy to improve the performance of carbon-based perovskite cells: The carbon-based perovskite cell is irradiated by low-intensity ultraviolet light to induce Pb I2 at the grain boundary of the perovskite film to form a grain boundary-passivated perovskite film.Electron micrographs and XRD measurements showed that low-intensity UV irradiation induced Pb I2 at the grain boundary of perovskite film.Kelvin scanning probe(SKPM)and Raman spectroscopy were used to test the surface potential and elemental changes of perovskite film after low-intensity UV irradiation.It is further proved that Pb I2 is also formed on the surface of the perovskite film.Through the steady-state fluorescence and time-resolved photoluminescence spectroscopy(TRPL)tests on the perovskite film,it was confirmed that the low-intensity UV-induced Pb I2 can inactivate the perovskite thin grain boundary and effectively reduce the perovskite.The non-radiative path in the film suppresses the recombination of carriers and promotes balanced transport of photogenerated carriers.The carbon-based hole-free transport layer PSC prepared based on the low-intensity ultraviolet-induced perovskite film finally obtained up to 15.97% of PCE.Although low-intensity ultraviolet light irradiation can improve the performance of carbon-based PSC,it is inevitable to work under normal sunlight,and ultraviolet light in sunlight can cause battery performance degradation.In order to solve this problem,we introduced a molybdenum-doped titanium dioxide(Mo-Ti O2)spacer layer between the Ti O2 mesoporous layer and the perovskite layer.In this paper,a one-pot hydrothermal method is used to prepare Mo-doped Ti O2(Mo-Ti O2)interlayer for carbon-based perovskite solar cells.Introduction of Mo-Ti O2 interlayer leads to an increase in the photostability of the PSC device by conversing ultraviolet light into free electrons through the redox shuttle between Mo(VI)and Mo(V).As a result,the PSC device based on the Mo-Ti O2 interlayer exhibits 22% and 23% PCE boost after receiving 2 hours of UV light and 1sun illumination respectively,and its long-term(120 h)photostability under 1sun illumination is also greatly enhanced compared with the PSC device without Mo-Ti O2 interlayer.