Researchers from China's Tianshui Normal University have reported a grain regeneration and passivation approach that can decrease the recombination loss of the perovskite layer/charge transfer layer interface and the grain border.
Device manufacturing process. Image from: Scientific Reports
The team relies on guanidine iodide (GAI) treatment of perovskite films for this new approach. Unlike most methods that use GAI for post-treatment of the perovskite layer or add GAI into the perovskite precursor solution, this work uses GAI for pre-treatment before spin coating the perovskite layer. It can effectively passivate surface defects and increase the grain size of perovskite films by controlling the crystallization process.
The results demonstrated that the GAI addition can control the crystallization process of perovskite grains and lower the density of defect states, smoothing out the grain borders and improving the smoothness of perovskite film. The passivation approach ultimately led to an improvement in the efficiency and moisture stability of PSCs.
The scientists showed that the water stability of devices was enhanced, the short-circuit current (Jsc), fill factor (FF), and power conversion efficiency (PCE) of PSCs were markedly improved, and non-radiative recombination was successfully reduced.
The best efficiency of PSCs was 20.56% after the additional GAI treatment was applied to the perovskite layer, an 11.9% increase over the efficiency of the control device without GAI treatment.
The team presented a passivation technique for grains that lowers recombination losses in perovskites at the interface between the HTL and grain boundaries at the same time. This research has the potential to increase cell stability, offer a practical process for producing straightforward and effective PSCs, and speed up the commercialization of perovskite solar technology. This method has the advantage of being simple and straightforward, providing a feasible pathway for the low-cost preparation and commercialization of PSCs.
