Flexible Planar Heterojunction Perovskite Solar Cells Fabricated via Sequential Roll‐to‐Roll Microgravure Printing and Slot‐Die Coating Deposition

Abstract

It is highly desirable to develop large‐scale, low‐cost fabrication processes for flexible perovskite solar cells (f‐PSCs) under ambient conditions for accelerating their potential commercialization. Roll‐to‐roll (R2R) printing technology enables high‐output manufacturing and is well suited for commercially processing f‐PSCs. Herein, triple‐cation f‐PSCs are developed with a planar heterojunction structure consisting of polyethylene‐2,6‐naphthalate/indium tin oxide/SnO2/perovskite/spiro‐OMeTAD/Ag via a combination of R2R microgravure printing and slot‐die coating under ambient conditions with a relative humidity of ≈40%. A mixture of isopropanol and water is used to dilute an as‐purchased SnO2 colloid solution and modify the contact between the electron‐transport layer (ETL) and substrate, leading to a smooth morphology of the R2R‐printed ETL SnO2 layer. Furthermore, suitable intrinsic organic salt additives and the N2 gas blowing‐assisted process are introduced to effectively improve the crystallization of the perovskite, resulting in a high‐quality perovskite film via R2R. After the optimization, the f‐PSCs based on the R2R‐printed ETL SnO2 and the perovskite film under an ambient condition show a power conversion efficiency (PCE) of up to 10.56% and an average PCE of 9.97%. This study provides a potential strategy for commercially fabricating f‐PSCs via a scalable and efficient R2R printing process.

Ambient Fabrication of Organic–Inorganic Hybrid Perovskite Solar Cells

“…The triple cation MA/FA/Cs PSCs were fabricated under 40% RH and obtained a highest PCE of 10.57% with total area of 15 × 15 mm 2 and the active area of 7 mm 2 . [210] Mixed MA/FA organic halide salts were used as additives to prevent the overgrowth of PbI 2 from ambient fabrication conditions and to promote the transformation in the next step, and a nitrogen gas knife was employed to accelerate the evaporation of solvent and improve the film quality. Gao et al [61] developed a novel multiflow air knife (MAK) to control the formation of large area perovskite films in ambient conditions.…”

Roll-to-roll gravure-printed flexible perovskite solar cells using eco-friendly antisolvent bathing with wide processing window

“…Spiro-OMeTAD was either spin-coated or solution shear-coated, the same as the table-top printed perovskite. PSCs composed of R2R printed SnO 2 /(FAPbI 3 ) 0.95 (MAPbBr 3 ) 0.05 and spin-coated Spiro-OMeTAD result in a high PCE of 16.7%, which is the best efficiency among PSCs from R2R-processed perovskite 13 , 14 , 46 , 47 . Solution shear-coating of Spiro-OMeTAD was also applied to the R2R-processed perovskite, resulting in a device with 16.5% of PCE, which value is almost the same to that from spin-coated HTL.…”

Recent Advances of Device Components toward Efficient Flexible Perovskite Solar Cells

“…Some groups have pioneered to fabricate FPSCs with the roll‐to‐roll technique. Gong et al manufactured flexible planar heterojunction PSCs with a PCE of 10.56% via roll‐to‐roll microgravure printing and slot‐d, i.e., coating deposition . Zuo et al fabricated FPSC devices of 0.1 cm 2 with the so‐called one‐step roll‐to‐roll air process and achieved a PCE of 11.16% .…”

“…Meanwhile, researches have been extensively conducted to push both rigid and FPSCs toward commercialization, for which the realization of large‐scale devices is the first step. Although the flexible nature of perovskites allow industrial roll‐to‐roll fabrication processes, there still remain concerns upon the scaling‐up of pinhole‐free perovskite crystallization processes …”