Perovskite Solar Cells: Current Trends in Graphene‐Based Materials for Transparent Conductive Electrodes, Active Layers, Charge Transport Layers, and Encapsulation Layers

Abstract

Recent advancements in technology have inevitably led to a significant increase in the global energy demand, whose traditional energy sources, such as fossil fuels and nuclear energy, are failing to meet needs due to their nonrenewable nature and consequent depletion. [1][2][3][4][5][6] Moreover, fossil fuels and nuclear energy are major sources of environmental pollution, which is responsible for unfavorable global warming and climate change. [7][8][9] Hence, there has been considerable research interest in sustainable and renewable energy sources, particularly solar energy, due to its natural abundance and environmentally friendly nature. [10][11][12] In this regard, solar energy is most commonly converted into electricity by making use of the first-generation solar cells, i.e., crystalline silicon solar cells, that are now commercially available, with high power conversion efficiencies (PCEs) of above 26% [13,14] and superior environmental stability. [15] However, the largescale production of silicon-based solar cells is restricted by their high production cost, complicated fabrication procedures, rigidity, [16,17] and PCE, which is almost close to the theoretical limit of %29.4%. [18] As a result, the second-generation solar cells, i.e., thin-film solar cells, such as amorphous silicon (a-Si) solar cells, copper indium gallium selenide (CIGS) solar cells, and cadmium telluride (CdTe) solar cells, [19][20][21] and the third-generation solar cells, such as organic solar cells (OSCs), perovskite solar cells (PSCs), and dye-sensitized solar cells (DSSCs), [22][23][24][25][26][27] have been developed by using simple and low-cost fabrication procedures. Among these, the thirdgeneration solar cells have gained significant research attention due to an abundance of low-cost materials, solution processability, flexibility, lightweight, environmental friendliness, and ease of scaling-up. [28][29][30][31][32] Interestingly, PSCs are a rising star owing to their recent breakthrough in PCE, which has shown a rapid increase from 3.8% in 2009 [33,34] to %25.5% for the current state-of-the-art PSCs. [35] The superior performance of PSCs is mainly attributed to the exceptional properties of metal halide perovskites, including the large absorption coefficient, direct and tunable bandgap, low exciton binding energy at room temperature, ambipolar charge transport characteristics, high charge carrier mobility, slow recombination kinetics, and long electron-hole diffusion length. [36][37][38][39][40][41] Thus, metal halide perovskites are emerging semiconductor materials, described by the general formula of ABX 3 , where A is a monovalent cation, such as methylammonium (CH 3 NH 3 þ ; MA), formamidinium (CH 3 (NH 2 ) 2 þ ; FA), caesium (Cs þ ), or rubidium (Rb þ ); B is a divalent metal cation, such as lead (Pb 2þ ), tin (Sn 2þ ), or germanium (Ge 2þ ); and X is a halide anion, such as iodide (I À ), bromide (Br À ), or chloride (Cl À ).

A review of graphene derivative enhancers for perovskite solar cells

“… 94 Graphene derivatives have great potential in improving some of the most significant drawbacks of optimising PSCs. Despite this great potential, the use of graphene-based materials in PSCs is still at primitive stages; 42 and, hence, needs constant review to reveal their potential holistically.…”

“…53,54 Additionally, the commercialisation and large-scale production of PSCs is also hindered by toxicity issues due to the use of solvents, 43 such as DMF, 43 g-butyrolactone (GBL), 55 chlorobenzene and toluene, 12,19 and Ag and Pb as counter electrodes. 21,42 Notwithstanding the fact that the toxicity of Pb(II) salts is a problem, studies are yet to provide a lucrative prospective substitute material to Pb-based PSCs. 56 Possible substitutes being considered include elements in the same periodic group, Sn and Ge; however, their toxicity, stability and band gap still need tailoring to achieve comparable absorption and PCEs.…”

“…The PCE of PSCs has dramatically increased from about 10% in 2012 31 to a certified value of 25.5% by 2019, 32,33 which is comparable to the 26% PCE of monocrystalline Si-based solar cells. 33–43 PSCs are well-positioned to be successfully commercialised since their PCE has surpassed other thin film-based solar cells (CIGS: 23% and CdTe: 22%). 33,44,45 This significant improvement of PCE within the last decade is mainly attributed to morphological tailoring and compositional engineering of the PSC device layers.…”

Metal‐organic chemical vapor deposition of anatase titania on multiwalled carbon nanotubes for electrochemical capacitors

“…The continuous growth in the global population and advances in technology have triggered high demands for clean, sustainable, and renewable energy, and effective energy storage systems. [1][2][3][4][5] Electrical energy storage systems include batteries, 6 compressed air, 7 flywheels, 8 pumped hydro-energy, 9 conventional capacitors 10 and electrochemical capacitors (ECs). 11 ECs bridge the gap between batteries and conventional capacitors as emerging energy storage and power supply devices 2,12,13 due to environmental compatibility, lower costs, potentially higher energy and power densities, low-temperature dependencies, and better cyclabilities than conventional capacitors.…”

“…The continuous growth in the global population and advances in technology have triggered high demands for clean, sustainable, and renewable energy, and effective energy storage systems 1–5 . Electrical energy storage systems include batteries, 6 compressed air, 7 flywheels, 8 pumped hydro‐energy, 9 conventional capacitors 10 and electrochemical capacitors (ECs) 11 .…”