A Regularity‐Based Fullerene Interfacial Layer for Efficient and Stable Perovskite Solar Cells via Blade‐Coating

Abstract

The electron transport layer (ETL) plays a crucial part in extracting electron carriers while optimizing the interfacial contact of perovskite/electrode in planar heterojunction perovskite solar cells (PVSCs). Despite various ETLs being designed for efficient PVSCs, there exists hardly any research on the effect of molecular stacking order on device performance. Herein, poly(ethylene-covinyl acetate) (EVA) is employed as the [6,6]-phenyl-C 61 -butyric acid methyl ester (PC 61 BM) solution additive. The strong binding energy between EVA with PC 61 BM promotes the molecular stacking order of ETLs, which alleviates the morphology inhomogeneity, possesses a matched energy level, blocks ion migration, and improves the water-oxygen barrier of perovskite devices. The blade-coated MAPbI 3 -based PVSCs achieve a power conversion efficiency (PCE) of 19.32% with positive reproducibility and negligible hysteresis, as well as maintain 90% and 80% of the initial PCE after storage under inert and ambient conditions (52% humidity) for 1500 h without encapsulation. This strategy also improves the champion PCE of CsFAMA-based PVSCs to 20.33%. These findings demonstrate that the regulation of molecular stacking order is a valid approach to optimize interfacial charge-carrier recombination in PVSCs, which meet the demand for high-performance ETL in large-area PVSCs and improve the upscaling of the fabrication technology toward practical applications.

Ink Engineering in Blade‐Coating Large‐Area Perovskite Solar Cells

“…Moreover, the fully blade-coated triple cation (CsFAMA based) PSCs with PC 61 BM/EVA ETLs achieved a champion PCE of 20.33%, demonstrating the universality of the molecular stacking strategy to optimize interfacial contacts of the PSCs. [108] Bagnis et al fabricated fully blade-coated PSCs with an inverted structure of glass/ITO/PEDOT:PSS/MAPbI 3 /PC 61 BM/ bathocuproine (BCP)/Ag in ambient air at humidity range [108] Copyright 2021, Wiley-VCH.…”

“…Moreover, the fully blade‐coated triple cation (CsFAMA based) PSCs with PC 61 BM/EVA ETLs achieved a champion PCE of 20.33%, demonstrating the universality of the molecular stacking strategy to optimize interfacial contacts of the PSCs. [ 108 ]…”

“…d) Cross-sectional SEM images of the MA-based solar cells with PCBM (left) and PCBM/EVA (right) as ETLs. Reproduced with permission [108]. Copyright 2021, Wiley-VCH.…”

Blading of Conformal Electron‐Transport Layers in p–i–n Perovskite Solar Cells

“…There are already several attempts to fabricate perovskite solar cells by all solution process using scalable coating methods. [11][12][13] However, these studies only resulted in devices with much lower performance than those made of evaporated ETL. For example, few attempts to fabricate PCS with all the bladed layers except evaporation of metal contact delivered a maximum power conversion efficiency (PCE) ranging from 14.9% to 20.3%.…”

“…For example, few attempts to fabricate PCS with all the bladed layers except evaporation of metal contact delivered a maximum power conversion efficiency (PCE) ranging from 14.9% to 20.3%. [11,12] Other studies reported fully spray-coated PSCs but with relatively lower efficiency ranging from 9% to 12%. [13,14] Slot-die coating reported to print the PCBM layer and other layers on flexible substrates showed much lower efficiency (2.9-11.2%) compared to those of aforementioned techniques.…”