Accelerating Thermal Transfer in Perovskite Films for High-Efficiency and Stable Photovoltaics

Heat accumulation within in-service perovskite solar cells (PSCs) under light irradiation is one imminent threat in deteriorating the persistent power output and long-term durability. Herein, a novel strategy is reported to remove dissipated heat by improving the thermal conductivity and thermal diffusivity of perovskite film with multi-walled carbon nanotubes (MWCNTs) as additives. Benefiting from the interaction between perovskite and MWCNTs as well as the accelerated heat transfer kinetics mediated by MWCNTs, this method produces a high-quality perovskite film with high crystallinity and reduced defects. Meanwhile, the incorporation of MWCNTs self-cools the operational temperature of final PSC from 42.5 to 38.5 °C to compensate the high temperature-induced performance reduction. Consequently, a significantly improved efficiency of 11.78% for carbon-based CsPbIBr 2 cell, 15.14% for carbon-based CsPbI 2 Br cell, 22.13% and 23.05% for regular and inverted (FA 0.83 MA 0.17 ) 0.95 Cs 0.05 Pb(I 0.9 Br 0.1 ) 3 cells, respectively, is achieved. Apart from the larger power conversion efficiency conservation rate > 94% over 2800 h in air without encapsulation, the optimal device demonstrates significant stability improvement by nearly 1.5-times after thermal aging at 85 °C for 1300 h and 40-fold after persistent operation for 350 h, providing a new path for high-efficiency and stable perovskite platforms.