Flexible Perovskite Solar Modules with Functional Layers Fully Vacuum Deposited

Large-area homogeneous and uniform perovskite films are key to the mass production of perovskite solar cells, especially the flexible ones. Different from the solution-processed preparation, herein an all-evaporation technique is developed for both perovskite films and the hole-transporting layer in the modules. With the two-step strategy of active-layer design, homogeneous large-area perovskite films are prepared via evaporation of first PbI₂ and then CH₃NH₃I. An 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ)-doped 4,4′,4″-tris(N-(aphthalene-2-yl)-N-phenylamino)triphenylamine (2T-NATA) hybrid hole-transporting layer is deposited on the indium-tin-oxide electrode via coevaporation. A power conversion efficiency (PCE) beyond 13% is achieved with the as-prepared flexible perovskite solar module (active area of 16.0 cm²), which exhibits both higher stability and higher efficiency than the conventional solution-processed module using poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) as the hole-transporting material. This novel strategy of all-evaporation functional layers provides a feasible way for the industrialization of flexible perovskite solar cells.