Tris(pentafluorophenyl)borane‐Modified P3CT‐K as an Efficient Hole‐Transport Layer for Inverted Planar MAPbI₃ Perovskite Solar Cells

Abstract

Polythiophene‐acid‐based conjugated polyelectrolytes have shown great potential as hole‐transport materials for the fabrication of inverted planar perovskite devices with decent power conversion efficiencies (PCEs), benefiting from their tunable structure and functional properties. In contrast to the current progress mainly from side functional group modification, here a simple and effective strategy is reported to effectively regulate the aggregation of P3CT‐K through the modification of the thiophene units in the main chain. A small molecule tris(pentafluorophenyl)borane (TPB) is applied as the Lewis acid to interact with the thiophene unit of polythiophene chain and regulate the aggregation of conjugated polyelectrolytes. The control of aggregation of P3CT‐K not only elevates the hole mobility of P3CT‐K, but also suppresses charge recombination in P3CT‐K composite films. Consequently, the high efficiency of inverted MAPbI3 perovskite solar cells is achieved with a peak power conversion efficiency of 20.7% and simultaneously improved short‐circuit current density and fill factor. This work provides an effective method for the aggregation control of the polyelectrolyte hole materials to promote the performance of inverted planar perovskite solar cells.

Thiourea Small Molecules Regulated Slow Passivation in MAPbI3 Thin Films for Enhanced Stability and Performance of Perovskite Solar Cells

“…Besides, a high efficiency of about 23.3% is achieved for inverted perovskite solar cells by using one-step spin coating, i.e., a low-temperature solution processing technique . In the inverted perovskite solar cells, indium tin oxide (ITO) glass is used as a substrate, and the surface of ITO is modified using polymers like P3CT-X (poly­[3-(4-carboxybutyl)­thiophene-2,5-diyl] (X: Na, K, Rb, or Cs)) and PTAA (poly­[bis­(4-phenyl)­(2,4,6-trimethylphenyl)­amine]). − The alkali ion end of the P3CT-X polymer acts as a nucleation site for polycrystalline perovskite thin films, which yields sub-micrometer-sized perovskite grains . In the grain boundaries of the polycrystalline perovskite thin films, defects, and impurities are inevitable, which are detrimental to the stability and photovoltaic performance of perovskite solar cells. − Also, the hydrophilic polycrystalline perovskite thin films are covered with the hydrophobic fullerene-based electron transport layer, so interfacial defects are ubiquitous .…”

Methylammonium Compensation Effects in MAPbI3 Perovskite Solar Cells for High-Quality Inorganic CuSCN Hole Transport Layers

“…Introducing a solid-state HEM resulted in a noticeable enhancement in the PCE of the PSCs. Since then, significant research on the design of novel device architectures, careful control of the morphology of each layer, and optimization of interfacial characteristics have enhanced the PCEs of PSCs. − …”

Unveiling the Critical Role of Oxidants and Additives in Doped Spiro-OMeTAD toward Stable and Efficient Perovskite Solar Cells

“…The photovoltaic (PV) technology, directly converting sunlight into electricity, has been recognized as one of the most promising and affordable renewable technologies . Recently, organic–inorganic hybrid perovskite semiconductors have become promising light-absorbing materials in solar cells because of their long carrier diffusion length, high carrier mobility, remarkable defect tolerance, and simple solvent-processed fabrication. , To date, the power conversion efficiency (PCE) has reached over 25% for single-junction perovskite solar cells (PSCs) after extensive optimization in charge dynamics, device structure, interfacial passivation, and functional material engineering. − Among the different functional layers in devices, hole transport materials (HTMs) are recognized as key components due to their crucial roles in device efficiency as well as stability. − HTM is located on top of the perovskite layer in n-i-p PSCs, which requires a high thickness for barrier protection (avoiding direct contact between Ag or moisture and perovskite), as well as a high electrical conductivity for charge collection. Balancing these two factors is important for achieving both high PCEs and stability of devices .…”