Facet-orientation-enhanced thermal transfer for temperature-insensitive and stable p-i-n perovskite solar cells

Persistent operation inevitably elevates the temperature of perovskite solar cells (PSCs), posing a challenge for maximizing their power output and stability even after effective defect passivation and encapsulation techniques have been implemented. Regulating the thermal conductivity of halide perovskites by additive engineering is now a mainstream strategy for achieving self-cooling devices, but our fundamental understanding of how perovskites with atomic disorder function remains insufficient. This theoretical study unveils the underlying mechanism of facet-dependent thermodynamic properties in mixed-cation perovskites. The results demonstrate that the (100) facet has higher thermal conductivity than the (110) and (111) facets. By carefully controlling the (100) crystallographic orientation through buried and bulk modification, the thermal conductivity of the target perovskite film can be increased from 1.005 to 1.068 ​W ​m⁻¹ ​K⁻¹, which lowers the PSC's equilibrium temperature 5.25 ​°C by accelerating heat transport and dissipation. Consequently, we achieve an inverted PSC with an excellent efficiency of 25.12%, accompanied by a significantly reduced temperature coefficient and better long-term stability: a conservation rate exceeding 90% after aging at 85 ​°C and exposure to persistent light irradiation for 1100 ​h. This work elucidates a previously unidentified outcome of crystal facet engineering: the achievement of thermal management in high-performance PSCs.