Perovskite solar cells (PeSCs) have been considered one of the competitive next generation power sources. To date, light-to-electric conversion efficiencies have rapidly increased to over 10%, and further improvements are expected. However, the poor device reproducibility of PeSCs ascribed to their inhomogeneously covered film morphology has hindered their practical application. Here, we demonstrate high-performance PeSCs with superior reproducibility by introducing small amounts of N-cyclohexyl-2-pyrrolidone (CHP) as a morphology controller into N,N-dimethylformamide (DMF). As a result, highly homogeneous film morphology, similar to that achieved by vacuum-deposition methods, as well as a high PCE of 10% and an extremely small performance deviation within 0.14% were achieved. This study represents a method for realizing efficient and reproducible planar heterojunction (PHJ) PeSCs through morphology control, taking a major step forward in the low-cost and rapid production of PeSCs by solving one of the biggest problems of PHJ perovskite photovoltaic technology through a facile method.

Recently, many kinds of printing processes have been studied to fabricate perovskite solar cells (PeSCs) for mass production. Among them, slot-die coating is a promising candidate for roll-to-roll processing because of high-throughput, easy module patterning, and a premetered coating system. In this work, we employed mixed lead precursors consisting of PbAc and PbCl to fabricate PeSCs via slot-die coating. We observed that slot-die-coated perovskite films based on the mixed lead precursors exhibited well-grown and uniform morphology, which was hard to achieve by using only a single lead source. Consequently, PeSCs made with this precursor system showed improved device performance and reproducibility over single PbAc. Lastly, a large-area module with an active area of 10 cm was fabricated with a power conversion efficiency of 8.3%.

Organometallic halide perovskite-based solar cells have exhibited rapidly increasing efficiencies through the use of mesoporous composites. The addition of materials used in organic solar cells to perovskite-based solar cells (PSCs) enables the fabrication of low-cost, flexible, low-temperature, solutionprocessed PSCs. However, obtaining sufficient coverage of the organic layer, usually poly(3,4-ethylenedioxythiophene)−poly(styrenesulfonate) (PEDOT:PSS), with CH 3 NH 3 PbI 3−x Cl x films remains difficult in spite of the advances. In this study, we investigated the influence of controlling the solvent evaporation rate on the degree of PEDOT:PSS surface coverage by CH 3 NH 3 PbI 3−x Cl x . We determined that an adequately fast spinning speed, drying at room temperature, and stepwise ramp annealing are critical for obtaining optimized planar hybrid perovskite solar cells with an ITO/PEDOT:PSS/CH 3 NH 3 PbI 3−x Cl x /PCBM/Al structure and efficiencies of up to 11.8%.