Researchers from The Hong Kong Polytechnic University, Beijing Institute of Technology and University of California Los Angeles have addressed the fragile and moisture-sensitive nature of halide perovskite materials by using an asynchronous cross-linking strategy.
Schematic illustration of intermediate-dominated perovskite crystallization by pre-embedded DVS and all-around co-polymerization protection through the post-treatment of gly. Image credit: Nature Communications
A multifunctional cross-linking initiator, divinyl sulfone (DVS), is firstly pre-embedded into perovskite precursor solutions. DVS facilitates intermediate-dominated perovskite crystallization manipulation, favoring formamidine-DVS based solvate transition. Subsequently, DVS-embedded perovskite as-cast films are post-treated with a nucleophilic reagent, glycerinum, to trigger controllably three-dimensional co-polymerization. The resulting cross-linking scaffold provides enhanced water-resistance, releases residual tensile strain, and suppresses deep-level defects.
The team achieved a maximum efficiency of over 25% (certified 24.6%) and a maximum VOC of 1.229 V, corresponding to a 0.30 V deficit, reaching 97.5% of the theoretical limit, which is said by the team to be the highest reported in all perovskite systems.
This work provides a strategy to synergically implement delicate perovskite crystallization manipulation and provide all-around protection at the perovskite surface and grain boundaries during the perovskite forming process. This strategy improved the moisture resistance of perovskite films, and achieved much enhanced devices stability, which may advance the commercialization of perovskite solar technology.
