Using an Airbrush Pen for Layer-by-Layer Growth of Continuous Perovskite Thin Films for Hybrid Solar Cells

In this manuscript we describe hybrid heterojunction solar cells, having the device architecture glass/indium tin oxide/poly(3,4-ethylenedioxythiopene)/poly(styrenesulfonic acid)/perovskite/[6,6]-phenyl-C61-butyric acid methyl ester/C60/2,9-dimethyl- 4,7-diphenyl-1,10-phenanthroline/Al, fabricated using lead halide perovskite obtained through spray-coating at a low precursor concentration. To study the relationship between the morphology and device performance, we recorded scanning electron microscopy images of perovskite films prepared at various precursor ratios, spray volumes, substrate temperatures, and postspray annealing temperatures. Optimization of the spray conditions ensured uniform film growth and high surface area coverage at low substrate temperatures. Lead halide perovskite solar cells prepared under the optimal conditions displayed an average power conversion efficiency (PCE) of approximately 9.2%, with 85% of such devices having efficiencies of greater than 8.3%. The best-performing device exhibited a short-circuit current density of 17.3 mA cm–2, a fill factor of 0.63, and an open-circuit voltage of 0.93 V, resulting in a PCE of 10.2%. Because spray-coating technology allows large-area deposition, we also fabricated devices having areas of 60 and 342 mm2, achieving PCEs with these devices of 6.88 and 4.66%, respectively.