High‐Performance Fully Printable Perovskite Solar Cells via Blade‐Coating Technique under the Ambient Condition

In order to fabricate large-area PVSCs, one of the critical challenges is to understand the infl uence of ambient environment on resultant perovskite thin-fi lms since perovskite crystals are sensitive to humidity under ambient condition. It has been shown that perovskite crystals degrade gradually when they are in contact with ambient moisture for certain time. [ 31,32 ] Therefore, most of the high performance perovskite solar cells are prepared in glovebox to avoid contacting moisture. However, fabricating PVSCs under ambient condition is inevitable if we desire to transition from laboratory research into large-scale applications. Lately, there are several encouraging reports about allowing limited amount of moisture to facilitate the perovskite crystallization and improve the performance of resulting device. [ 33,34 ] However, there are no detailed underlying mechanisms explained on how moisture affects perovskite crystallization so far. To alleviate these problems, we have investigated the feasibility of achieving fully printable PVSCs by the blade-coating technique under the ambient condition. The blade-coating fabrication has been widely used to fabricate OSCs and is proven to be a simple, environment-friendly, and low-cost method for the solution-processed photovoltaic. Compared to the screen printing, it not only can print nanoparticles, but also can print all kinds of solutions with any concentration. Moreover, the fi lm morphology control of the blade-coating method is much better than the spray coating and roll-to-roll printing; high-quality photoactive layers with controllable thickness can be accomplished by using a precisely translational blade under the ambient condition with controlled relative humidity. The PVSCs with a confi guration of ITO/poly(3,4-ethylenedioxy-thiophene):poly(4-styrenesulfonate) (PEDOT:PSS)/ CH 3 NH 3 PbI X Cl 3− X /[6,6]-phenyl-C 61 butyric acid methyl ester (PC 61 BM)/Bis-C 60 /Ag were fabricated to realize the fully printable process, as illustrated in Figure 1 a. All constituent interlayers, except for the Ag top electrode, were prepared via blade-coating. The coating conditions were optimized to allow the preparation of high-quality interlayer fi lms. Especially, the effect of humidity was carefully investigated and monitored to facilitate the crystallization of perovskite fi lms under ambient condition. Finally, high PCE (10.44% ± 0.23%) device could be achieved after optimizing the blade-coating process and relative humidity in environment. Moreover, a high-performance fl exible PVSC with a PCE of 7.14% ± 0.31% was demonstrated for the fi rst time using this low-temperature (<150 °C) fully printable process. The exceptional photovoltaic properties demonstrated recently for organic–inorganic halide perovskites (such as CH 3 NH 3 PbX 3 (X = Cl, Br, or I)) have attracted great attention from researchers. [ 1–8 ] The promising features of these perovskites include broad and intense absorption spectra, [ 9 ] appropriate semiconducting properties, [ 10 ] long carrier diffusion length, [ 11,12 ]