Study On Application Of MXene And Its Composites On All-Inorganic Perovskite Solar Cells

In recent years,organic-inorganic hybrid perovskite solar cells have shown remarkable performance in optoelectronic properties,but their poor humidity and thermal stability have hindered their commercial application.All-inorganic perovskite solar cells are expected to improve the above problems,and significant progress has been made in component engineering,interface regulation,and device structure optimization.However,there are still many problems in practical applications,such as unreasonable device structure design resulting in large energy loss,non-radiative recombination of charge carriers at grain boundaries/interfaces,etc.,which affect the lifespan of all-inorganic perovskite solar cells.Two-dimensional materials have advantages such as tunable bandgap,high carrier mobility,and matching energy level structure with perovskite materials,and can be used for interface regulation of perovskite solar cells.MXene is a new two-dimensional（2D）nano-material composed of transition metal carbide/nitride,which has advantages such as high conductivity,tunable surface functional groups,and tunable work function.It has great potential in improving the photoelectric efficiency,carrier lifespan,and device stability of perovskite solar cells.Therefore,this paper further optimized the performance of Ti₃C₂T_xMXene by grafting surface functional groups and constructing heterojunctions,and applied it to all-inorganic perovskite solar cells to improve the photoelectric conversion efficiency and stability of the devices.The mechanism of its effect on the surface of perovskite materials was also studied.The main research content and results of this paper are as follows:（1）Ti₃C₂T_xMXene/Graphene Oxide（GO）two-dimensional heterojunctions were prepared by ultrasonic intercalation,and used as modifying materials for all-inorganic perovskite solar cells.The Ti₃C₂T_xMXene/GO heterojunction repaired the oxygen-containing complex centers on the surface of GO nanosheets,thereby improving the carrier mobility of the material.The Ti₃C₂T_xMXene/GO heterojunction exhibited better hole extraction ability than pure MXene and GO,and also enhanced the energy level matching between the perovskite absorption layer and the carbon electrode.Therefore,the photoelectric performance parameters such as V_oc,J_sc,and FF of the devices were significantly improved.The photoelectric conversion efficiency of the CsPbIBr₂and CsPbI₂Br devices modified by it were 11.07%and15.04%,respectively.In addition,the stability of both devices was also significantly improved.（2）A stretchable MXene,succinimide-modified MXene（SAM）,was prepared,and the rich and tunable surface functional groups of Ti₃C₂T_xMXene were utilized to graft succinimide on the surface of Ti₃C₂T_xnanosheets through nucleophilic substitution reaction and dehydration reaction,and the dispersibility and surface structural properties of SAM in organic solvents were adjusted to improve its applicability as an additive for perovskite precursor solution.In addition,the stretchable alkyl chain can promote lattice contraction or expansion to form an elastic grain boundary,eliminate the spatial distribution stress in the perovskite film,and promote carrier transport.SAM was used in all-inorganic CsPbIBr₂and CsPbI₂Br perovskite solar cells,and the device performance was significantly improved,with photoelectric conversion efficiency reaching 11.06%and 14.30%,respectively.In addition,under harsh conditions,CsPbIBr₂and CsPbI₂Br devices still had good stability.