Passivating silicon-based hybrid solar cells through tuning PbI₂ content of perovskite coatings

Silicon-nanowire (SiNW) based hybrid solar cells generally suffered from severe defect trapping initiated from high density of dangling bonds at nanowire surfaces and thus, passivation process was highly demanded for suppressing the surface recombination of photogenerated carriers. In this study, the strategy was proposed for minimizing the possible charge recombination by using perovskite layer as passivation design while tuning the excess PbI₂ amount as well as employing the antisolvent treatment. The results indicated the uniform incorporation of perovskite coatings possessing 5% of excess PbI₂ prepared under chlorobenzene treatment with aligned SiNW arrays demonstrated the improved cell efficiency of 14.1%, approximately 1.4 times beyond the un-passivated solar cells. This was supported by the increased carrier lifetime as well as reduction of charge-transfer resistance that greatly benefited the improvement of open-circuit voltage and fill factor; in addition, the superior light absorption of hybrid perovskite/SiNW nanostructures was evidenced through experimental and simulated examinations that introduced the additional gain of short-circuit current density. Such hybrid design shed light on the realization of all-solution processed photovoltaic devices, and might further offer an innovative approach for other advanced optoelectronic applications.