Spray‐Cast Multilayer Organometal Perovskite Solar Cells Fabricated in Air

Abstract

Spray‐coating is a versatile coating technique that can be used to deposit functional films over large areas at speed. Here, spray‐coating is used to fabricate inverted perovskite solar cell devices in which all of the solution‐processible layers (PEDOT:PSS, perovskite, and PCBM) are deposited by ultrasonic spray‐casting in air. Using such techniques, all‐spray‐cast devices having a champion power conversion efficiency (PCE) of 9.9% are fabricated. Such performance compares favorably with reference devices spin‐cast under a nitrogen atmosphere that has a champion PCE of 12.8%. Losses in device efficiency are ascribed to lower surface coverage and reduced uniformity of the spray‐cast perovskite layer.

Coated and Printed Perovskites for Photovoltaic Applications

“…[105] Heo et al reported the highest PCE of 18.3% for spray-coated PSCs so far (see Figure 4b-d). [110] Very recently, Mohamad et al and Bishop et al reported all-spray-coated PSCs. [31] As a result, large perovskite grains exhibiting a low number of trap states were demonstrated using solvent mixtures of DMF and GBL in a ratio of 8:2.…”

“…[31] The study showed the significance of utilizing different boiling point solvents in various ratios to control the evaporation of solvents, but also relied on substrate heating at 120 °C. [109,110] Mohamad et al used PEDOT:PSS and PCBM as their HTL and ETL, respectively, achieving 9.9% efficient devices [110] while, Bishop et al achieved comparable device performance of 10.2% based on PSCs using spray-coated compact TiO 2 , mesoporous TiO 2 as ETLs and Spiro-OMeTAD as the HTL for their architecture. Moreover, the fabrication of 100 cm 2 large PV modules with an active area of 40 cm 2 and a PCE of up to 15.5% was realized.…”

“…Moreover, the fabrication of 100 cm 2 large PV modules with an active area of 40 cm 2 and a PCE of up to 15.5% was realized. [97,98,100] The main challenges of this technique are crystal-growth related thickness variations, [100,109] solution de-wetting [100] and nonuniform substrate coverage [48,100,110] arising from the surface tension driven coffee-ring [111] or Marangoni effects. In this study, the ink contained slow-drying solvents that were extracted in an antisolvent diethylether bath.…”

“…In this study, the ink contained slow-drying solvents that were extracted in an antisolvent diethylether bath. [99,100,109,110] Beyond control of process parameters, ink formulations using solvent mixtures and additives have been critical in addressing these issues. [106] The previous studies mentioned above covered the spray coating of the absorber layer only.…”

“…The solvent extraction in the antisolvent bath induced crystal nucleation, and a subsequent annealing at 150 °C promoted crystal growth, with the resulting devices reaching a maximum PCE of 17.3%. [31,109,110] However, for an industrial roll-to-roll process, it is desired to also spray-coat the ETL and HTL and possibly even the electrodes.…”