Post‐Treatment of Mesoporous Scaffolds for Enhanced Photovoltage of Triple‐Mesoscopic Perovskite Solar Cells

Abstract

Triple‐mesoscopic perovskite solar cells (PSCs) based on TiO2/ZrO2/carbon architecture have attracted much attention due to their excellent long‐term stability and screen‐printing technique‐based fabrication process. However, the relatively low open‐circuit voltage (VOC) limits the further improvement of power conversion efficiency (PCE) for triple‐mesoscopic PSCs. Herein, 2‐phenyl‐5‐benzimidazole sulfonate‐Na to post‐treat the triple‐mesoscopic structured scaffold is introduced. The conduction band of the mesoporous TiO2 layer (electron transport layer [ETL]) is significantly shifted up from −4.22 to −4.11 eV, which favors the electron transfer from the perovskite absorber to the ETL. At the same time, the recombination at the interface of ETL/perovskite is effectively suppressed. Correspondingly, the VOC and fill factor (FF) of the devices are enhanced without sacrificing the photocurrent density (JSC). With optimal post‐treatment conditions, the champion device delivers a VOC of 1.02 V and an FF of 0.70 with JSC of 23.06 mA cm−2, showing an overall PCE of 16.51%. After 1000 h continuous operation at the maximum power point under AM1.5G 1 sun illumination, the devices can maintain 91.7% of the initial efficiency. This simple procedure and significant photovoltage enhancement render this method promising for fabricating efficient PSCs based on mesoporous charge transport layers.

Triple-Mesoscopic Carbon Perovskite Solar Cells: Materials, Processing and Applications

“…Of trialled Na + , Li + and K + salts, Na + provided the best band-matching, and therefore the greatest device performance. Stacks treated with 3.5 µl of 0.05 M salt in a GBL/ethanol mix and annealed at 100 °C before MAPbI3 infiltration exhibited average PCEs of 15.76 ± 0.44% compared to control devices of 13.91 ± 0.38% efficiency [49].…”

“…As a result, the electron transfer from the perovskite absorber to the ETL was enhanced and recombination at the ETL/perovskite interface suppressed. Consequently, the open circuit voltage (V oc ) and FF of the devices were increased without sacrificing the J sc , with the champion device showing an overall PCE of 16.51% [49].…”

Tailoring the Dimensionality of Hybrid Perovskites in Mesoporous Carbon Electrodes for Type‐II Band Alignment and Enhanced Performance of Printable Hole‐Conductor‐Free Perovskite Solar Cells

“…By tuning the composition and crystallization of perovskite absorbers in the mesoporous scaffold, [ 13–15 ] modifying the mesoporous scaffold and interfaces [ 16,17 ] and developing novel deposition technique, [ 14 ] the efficiency of triple‐mesoscopic PSCs has been improved from the initial 6% to current 16.51%. [ 9,16,18,19 ] Particularly, the devices have been suffering severe potential loss, and thus showed low open‐circuit voltage ( V OC , 0.85–0.95 V). In one hand, the mesoporous scaffold is micrometer‐thick, which determines the charge diffusion length in the device.…”

Improving Hole‐Conductor‐Free Fully Printable Mesoscopic Perovskite Solar Cells’ Performance with Enhanced Open‐Circuit Voltage via the Octyltrimethylammonium Chloride Additive

“…[ 15 ] Sheng et al treated the printable triple mesoscopic films with 2‐phenyl‐5‐benzimidazole sulfonate‐X (X = Li, Na, and K) and enabled suitable band alignment between TiO 2 and perovskite for printable MPSCs. [ 16 ]…”