Inorganic Framework Composition Engineering for Scalable Fabrication of Perovskite/Silicon Tandem Solar Cells

The conformal and scalable growth of perovskite film
on industrially
textured silicon with a hybrid evaporation-solution method contributes
to sufficient light utilization and large-scale commercialization
of monolithic perovskite/silicon tandem solar cells. However, the
efficacy of this approach is hindered by the incomplete reaction during
the transition from spin-coating to blade-coating techniques, notably
involving the buried sublimation-PbI2. Herein, we demonstrate
a triple-source coevaporation (PbI2, PbCl2,
and CsBr) method combined with the framework-heat-treatment (FHT)
strategy. Such inorganic framework composition engineering generates
a quasi-two-dimensional layered structure, CsPb2X5, which enlarges the inorganic interlayer spacing and facilitates
the penetration of organic salt solution. Consequently, a high-quality
perovskite film with fully converted PbI2 has been achieved.
This advance translates into one of the best tandem solar cells that
has a stabilized efficiency of 28.3% (1.05 cm2). Impressively,
the encapsulated device retains 94% of its initial performance after
operating for more than 1200 h under 1-sun illumination in ambient
air.