Simultaneous Improvement of the Power Conversion Efficiency and Stability of Perovskite Solar Cells by Doping PMMA Polymer in Spiro‐OMeTAD‐Based Hole‐Transporting Layer

Abstract

Improving efficiency and stability has become an urgent issue in the application of perovskite solar cells (PSCs). Herein, a kind of long‐chain polymer or polymethylmethacrylate (PMMA) is added into the spiro‐OMeTAD matrix to improve the film formation process and hence the device performance. It is observed that, after modification, the spiro‐OMeTAD‐based hole‐transporting layer becomes uniform, continuous, and condensed. Meanwhile, the power conversion efficiency of the devices is upgraded. Compared with the control device, open‐circuit voltage of the modified one (with moderate doping) increases from 1.06 (±0.03) to 1.10 (±0.02) V, fill factor increases from 72.20 (±3.44)% to 75.59 (±3.35)%, and the power conversion efficiency increases from 18.82 (±1.06)% to 20.51 (±0.82)% (highest at 21.78%) under standard test condition (AM 1.5G, 100 mW cm−2). Transient photocurrent/photovoltage decay curves, time‐resolved photoluminance, and impedance spectroscopy studies show that the modification could accelerate charge transfer and retard interfacial recombination. In addition, the modification improves device stability. Due to the strengthened barrier against penetration of “H2O/O2/Ag,” the efficiency of the unsealed device could retain 91.49% (by average) of the initial one after 100 days storage in the dark [relative humidity = 30(±5)%]. This work shows that long‐chain polymer doping could simultaneously improve efficiency and stability of spiro‐OMeTAD‐based PSCs.

Stability Improvement of Perovskite Solar Cells by the Moisture-Resistant PMMA:Spiro-OMeTAD Hole Transport Layer

“…The long-term stability enhancement of the PMMA:spiro-OMeTAD vices is mainly attributed to the protective effect of water diffusion into the lig tion layer. The function of PMMA-doped spiro-OMeTAD was also confirmed sults from a recent study [30].…”

Spiro‐OMeTAD‐Based Hole Transport Layer Engineering toward Stable Perovskite Solar Cells

“…Xia et al introduced polymethyl methacrylate (PMMA), [104] a kind of long-chain polymer, into Spiro-OMeTAD to regulate the HTL formation process (Figure 11e) and improve the photovoltaic performance of PSCs. The Spiro-OMeTAD HTL incorporated with PMMA was homogeneous in morphology as revealed by the AFM analysis and it was in close contact with the bottom perovskite layer.…”

“…e) Schematic of the fabrication of PSCs using PMMA incorporated Spiro-OMeTAD and cross-sectional SEM image of a typical device. Reproduced with permission [104]. Copyright 2021, John Wiley and Sons.…”

Promotion Strategies of Hole Transport Materials by Electronic and Steric Controls for n–i–p Perovskite Solar Cells

“…[98] Besides some polymerization precursors, some polymers were introduced into o-HTLs, also acting as cross-linking additives to cohesive molecules and enhance organization of o-HTMs. [101] Xia et al and Kundu and Kelly used PMMA as additives in spiro-OMeTAD [99] and P3HT, [102] respectively. PMMA additives were considered to not only enhance the morphology of HTLs but also improve the conductivity of HTLs by manipulating their formation behavior (Figure 6 f).…”

“…Xia et al. and Kundu and Kelly used PMMA as additives in spiro‐OMeTAD [99] and P3HT, [102] respectively. PMMA additives were considered to not only enhance the morphology of HTLs but also improve the conductivity of HTLs by manipulating their formation behavior (Figure 6 f).…”