Study On Preparation And Performance Of Lead-free Bismuth-based Perovskite Light-absorbing Material

Perovskite solar cells have become a hotspot in the photovoltaic field due to their adjustable optical band gap,high absorption coefficient,low cost,and continuously improved conversion efficiency.However,due to the toxicity and instability of lead in traditional perovskite light-absorbing materials,its commercial production is seriously hindered.Therefore,it is very necessary to explore stable lead-free perovskite materials.Among them,the bismuth-based perovskite material is a relatively promising lead-free material.In this paper,two new non-toxic perovskite light-absorbing layer materials,bismuth-based perovskite(C6H4NH2)BiI4 and(C6H4NH2)2KBiI6,which can exist stably in the environment,were prepared.The main content is as follows:(1)(C6H4NH2)BiI4,a new perovskite light-absorbing layer material,was prepared by reacting bismuth iodide(BiI3)and 2-iodoaniline(C6H4NH2I)in proportion by using a one-step spin coating method.By exploring the optical properties and energy band structure of(C6H4NH2)BiI4 perovskite materials,the results show that(C6H4NH2)BiI4 perovskite material has good absorption in the visible light region,an optical band gap of 1.72 eV,and an absorption coefficient of 104 cm-1.It is an n-type semiconductor material.By exploring the optimal annealing conditions of(C6H4NH2)BiI4 films,it was found that(C6H4NH2)BiI4 films with good crystallinity,high coverage and low roughness were prepared at 90? for 30 min.The air,ultraviolet light and thermal stability of(C6H4NH2)BiI4 perovskite were explored,and the results showed that(C6H4NH2)BiI4 perovskite material has good air,light and thermal stability.(2)A new material(C6H4NH2)2KBiI6 for the perovskite light-absorbing layer was prepared by reacting bismuth iodide(BiI3),potassium iodide(KI)and 2-iodoaniline(C6H4NH2I)in proportion by using a one-step spin coating method.By exploring the optical properties and energy band structure of(C6H4NH2)2KBiI6 perovskite material,the results show that the(C6H4NH2)2KBiI6 perovskite material has good absorption in the visible light range,the optical band gap is 1.82 eV,the carrier lifetime is 1.21 ns,and the absorption coefficient is on the order of 104 cm-1,which is a kind of n-type semiconductor material.By exploring the optimal annealing conditions of(C6H4NH2)2KBiI6 films,it was found that(C6H4NH2)2KBiI6 films with good crystallinity and high coverage were prepared at 120? for 40 min.The air,ultraviolet light,and thermal stability of(C6H4NH2)2KBiI6 perovskite were explored.The results showed that(C6H4NH2)2KBiI6 perovskite material is relatively stable in the air,has a certain UV tolerance and good thermal stability.