Rear Electrode Materials for Perovskite Solar Cells

Abstract

Perovskite solar cells (PSCs) represent a promising next‐generation photovoltaic technology considering their high efficiency and low cost. At the current stage, resolving the stability bottleneck is extremely urgent to realize PSCs’ commercialization since the efficiencies of these cells are improved to a level comparable to that of crystalline silicon solar cells. Similar to other functional layers, a proper choice of the rear electrode atop the perovskite layer is equally important for achieving the device's long‐term stability. This topic has not been comprehensively reviewed before. Here, recent progress in the development of rear electrodes based on metals, carbon‐based materials, transparent conductive oxides, and conductive polymers is summarized, especially focusing on their different impacts on the device's long‐term stability and associated degradation mechanisms. In the context of practical applications, the impacts of rear electrode materials on the device's overall efficiency and cost‐effectiveness are also discussed.

The synergistic effect of defect passivation and energy level adjustment for low-temperature carbon-based CsPbI2Br perovskite solar cells

“…10 In terms of costs, both organic HTLs and metal electrodes are quite expensive, for example, the costs of poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA), Spiro-OMeTAD, Au and Ag are 19.80 $ per ml, 23.96 $ per ml, 60500 $ per kg and 8500 $ per kg, respectively. 11,12 The above disadvantages seriously hinder the practical application of PSCs. In principle, CsPbX 3 (X = I, Br, or mixed halides) carbonbased inorganic PSCs (C-IPSCs) can solve the above issues owing to the absence of organic components.…”

“…In principle, CsPbX 3 (X = I, Br, or mixed halides) carbonbased inorganic PSCs (C-IPSCs) can solve the above issues owing to the absence of organic components. Meanwhile, hydrophobic and environmentally friendly carbon materials as the HTLs and back electrodes also simplify the fabrication process, decrease the cost (300 $ per kg), 12 and protect perovskite films from moisture erosion. 8,13 Among all the CsPbX 3 perovskites, CsPbI 3 has a narrow band gap (E g ) of 1.73 eV, which is suitable for efficient PSCs but easily turns into the non-perovskite phase.…”

Recent advances in the interfacial engineering of organic–inorganic hybrid perovskite solar cells: a materials perspective

“…Currently, the most commonly used metal oxide transparent conductive films for the bottom electrode of PSCs are indium-doped tin oxide (ITO) and fluorine-doped tin oxide (FTO), etc., whose photovoltaic properties are closely related to the film thickness and film quality. 49,50 Among them, ITO is commonly used as the bottom electrode for planar structured PSCs. Compared with ITO, FTO has a lower light transmission rate due to its larger thickness, but it is more suitable as a substrate for interfacial layers that require high-temperature heating, such as TiO 2 , due to its corrosion resistance and hightemperature tolerance, and is therefore widely used as the bottom electrode for mesoporous structured PSCs.…”

“…In 2013, Han et al used a carbon electrode as the top electrode of the PSCs and prepared the first fully printed HTL-free PSCs, obtaining a PCE of 6.64%. 49,52 Since then, research into replacing the traditional noble metal with carbon as the top electrode has been gradually developed. However, this device structure has so far suffered from severe performance losses at the back electrode interface, including energy-level mismatch and ineffective hole extraction.…”

Counter electrodes for perovskite solar cells: materials, interfaces and device stability

“…1, in both n-i-p and p-i-n architectures, counter electrodes play critical roles in photovoltaic parameters as well as the device stability. 30,31 The main role of the counter This journal is © The Royal Society of Chemistry 2022 electrode is to extract, transfer and collect the charge carriers to enable the current generation. The transparency and flexibility of counter electrodes influence the light-absorption and the device mechanical stability, which also determines the device application areas, such as flexible or bifacial solar modules.…”