Multiply Charged Conjugated Polyelectrolytes as a Multifunctional Interlayer for Efficient and Scalable Perovskite Solar Cells

Abstract

A series of anionic conjugated polyelectrolytes (CPEs) is synthesized based on poly(fluorene‐co‐phenylene) by varying the side‐chain ionic density from two to six per repeat units (MPS2‐TMA, MPS4‐TMA, and MPS6‐TMA). The effect of MPS2, 4, 6‐TMA as interlayers on top of a hole‐extraction layer of poly(bis(4‐phenyl)‐2,4,6‐trimethylphenylamine (PTAA) is investigated in inverted perovskite solar cells (PeSCs). Owing to the improved wettability of perovskites on hydrophobic PTAA with the CPEs, the PeSCs with CPE interlayers demonstrate a significantly enhanced device performance, with negligible device‐to‐device dependence relative to the reference PeSC without CPEs. By increasing the ionic density in the MPS‐TMA interlayers, the wetting, interfacial defect passivation, and crystal growth of the perovskites are significantly improved without increasing the series resistance of the PeSCs. In particular, the open‐circuit voltage increases from 1.06 V for the PeSC with MPS2‐TMA to 1.11 V for the PeSC with MPS6‐TMA. The trap densities of the PeSCs with MPS2,4,6‐TMA are further analyzed using frequency‐dependent capacitance measurements. Finally, a large‐area (1 cm2) PeSC is successfully fabricated with MPS6‐TMA, showing a power conversion efficiency of 18.38% with negligible hysteresis and a stable power output under light soaking for 60 s.

Circularly Polarized Emission from Organic–Inorganic Hybrid Perovskites via Chiral Fano Resonances

“…Solution-processed hybrid organic–inorganic perovskites have recently attracted tremendous interest because of their exceptional optoelectronic properties. Long carrier diffusion lengths, low trap densities, large absorption coefficients, high photoluminescence (PL) quantum yields, large optical gain, and tunable band gap energy make hybrid perovskites ideal for various optoelectronic devices, such as solar cells, light-emitting diodes, lasers, and photodetectors. − In particular, emission wavelengths from hybrid perovskites can cover the whole visible range with compositional variations; thus, hybrid perovskites are being considered as new tunable semiconductor materials for efficient light sources. , …”

Laser-Assisted Ultrafast Fabrication of Crystalline Ta-Doped TiO2 for High-Humidity-Processed Perovskite Solar Cells

“… 40 , 41 Therefore, a better surface wettability of the Ta-TiO 2 films treated by the laser process could improve the contact at the TiO 2 /perovskite interface, promote a more uniform growth of the perovskite crystals, and reduce the formation of pinholes and defects. 42 − 44 …”

Synergy Effect of a π‐Conjugated Ionic Compound: Dual Interfacial Energy Level Regulation and Passivation to Promote Voc and Stability of Planar Perovskite Solar Cells

“…[33] However, some of these ionic compounds with small cations are insulators with high volatility, inevitably increasing series resistance and hindering charge extraction. [34] π-Conjugated organic cations have been introduced into perovskite to form surface band edges and grains and alter carrier dynamics, leading to higher efficiency and stability. [35,36] π-Conjugated ionic compounds are conductive and amphiphilic, consisting of a hydrophobic conjugated backbone with hydrophilic ionic side chains.…”