Study On Controllable Fabrication Of Micro-structured Perovskites Film With Laser Field

Perovskite has unique crystal structures and superior optical and electrical properties,coupled with the advantages of low-cost and simple synthesis and preparation,which makes it show huge commercial applications prospect in the fields of photovoltaic conversion,light-emitting devices,photodetection sensing,and catalysis.However,the commonly used thermal annealing treatment to promote perovskite crystallization is not conducive to the uniform growth of perovskite grain,usually leading to poor controllability in film morphology and grain size,which has a negative impact on the optoelectronic properties.On the other hand,the introduction of micro-nano structure on the surface of optoelectronic film is an effective method to regulate its optical properties and further improve the performance of optoelectronic devices.Therefore,for perovskite-based optoelectronic devices,the controlled crystallization and microstructure of perovskite film is of great significance for the improvement of device performance.However,due to the solubility in polar solvents and hydrolysis properties of perovskite,traditional micro-nano processing methods cannot be applied to the micro-nano structured preparation of perovskite films.Therefore,how to crystallize perovskite well while making them micro-structured remains a challenge.This paper focuses on the preparation of micro-nano structure of perovskite film.We proposed to employ laser four-beam interference to construct a cone-shaped light field distribution on the microscopic scale and a thermal field distribution corresponding to the light field is generated on the surface of the perovskite precursor wet film.The accumulation of heat over time will cause the rise of temperature,so there will be a temperature gradient at the boundary of the light and dark regions.Driven by this temperature gradient,the perovskite precursor wet film will nucleate,crystallize and grow further at the interference enhanced region,and finally obtain a methylamine lead iodine(MAPb I₃)perovskite film with good crystallization and periodic pyramidal microstructure corresponding to the optical field distribution.At the same time,by adjusting the parameters of the laser,the controllable preparation of periodic micro-structured perovskite films with different morphologies can be achieved.As a preliminary attempt,we fabricated solar cells based on microstructured perovskite thin films.After the perovskite precursor wet film without anti-solvent was treated with 44 m W/180 s laser beam,perovskite solar cells achieved efficiency enhancement of 28%.Moreover,the perovskite soler cells with anti-solvent and laser action,with the help of secondary thermal annealing for furtherly grains grow,the fabricated solar cell also have shown a slight efficiency improvement of 4%.The longer optical length caused by the scattering of microstructures improves the light absorption of perovskite films and contributes to the improvement of device efficiency.At present,the efficiency of microstructured perovskite cells prepared by laser is low.In the future work,we would paid more attention to optimize the preparation process of laser-induced microstructured perovskite film and device performance,and further explore the internal mechanism of interaction between laser field and perovskite film.