Perovskite microwires are a promising material for use in optoelectronics, due to their large surface-to-volume ratio and high photoelectric conversion efficiency. However, the optoelectrical performance of perovskite microwires can be greatly affected by their degree of crystallization.
Laser annealing is a powerful tool for crystallizing perovskite microwires, as it uses high light absorption to induce a fast heating process. In this research, a 405 nm violet laser located near the absorption peak of typical perovskite films was employed as the annealing laser. The laser beam was combined into the micro Raman measurement system, which was provided by ProTrusTech, known as MRID (Micro Raman Identification Dual Lasers). This design allowed for real-time information on the annealing and crystallization process to be provided.
The optical scheme of laser-induced thermal annealing and the polarized micro Raman system. ND Filter: neutral density filter
The proposed scheme used an mW-level continuous-wave laser beam to provide enough kinetic energy for crystalline in perovskite microwires. The thermal distribution of the perovskite microwire under the annealing laser beams was considered, and polarized Raman signals were used to provide evidence of the perovskite microwires' crystallization.
This work offered a novel approach of on-site, real-time laser-induced thermal annealing design for perovskite microwires. This approach can be used in other material procedures, and the intensity-dependent conditions were crucial for the annealing processes and analyzed in detail. Additionally, it was found that the substrate effect played a role in the annealing process. Overall, this proposed scheme provided integrated, novel, scalable, and highly effective designs of perovskite-based devices.
The OM image of a perovskite film (a) before and (b) after the laser beam illumination. A violet laser beam was focused by a 100X objective lens on the perovskite film. The laser beam diameter was measured as 2.6 m. (c) The thermal image pictured by a thermal infrared camera due to laser beam illumination.(d) The heating curve with time.
According to a study by Chen, Wang, Wu, Cheng, and Chui, published in the journal Photonics in January 2021, the research team demonstrated a novel approach of on-site, real-time laser-induced thermal annealing of CH3NH3PbI3 Perovskite Microwires using ProTrusTech's MRID (Micro Raman Identification Dual Lasers) system. The article is available at https://doi.org/10.3390/photonics8020030 . The paper was edited by Tien-Lung Chiu and Received on January 7th, Accepted on January 24th and published on January 26th, 2021.