Improving and Stabilizing Perovskite Solar Cells with Incorporation of Graphene in the Spiro-OMeTAD Layer: Suppressed Li Ions Migration and Improved Charge Extraction

Guo, Xiaochen; Li, Jian‐Yang; Wang, Bin; Zeng, Peng; Li, Faming; Yang, Qiang; Chen, Yuanfu; Liu, Mingzhen

doi:10.1021/acsaem.9b02037

Cited by 34 publications

(44 citation statements)

References 52 publications

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“…Among these, carbonbased materials, particularly graphene and its derivatives, are potential additives to the perovskite active layer material due to their wide absorption spectral range, high charge carrier mobility, and excellent thermal, chemical and mechanical stability, good crystallinity, and less impact on the environment. [45,159] In this regard, GO [160,161] and GO-Cl [162] have been introduced into the MAPbI 3 active layer of PSCs, as shown in Figure 6a. This significantly improved the crystallinity, morphology, optical absorption, and charge extraction efficiency of the perovskite film, together with reducing charge carrier recombination.…”

Section: Active Layermentioning

confidence: 99%

“…The charge transport layers help to reduce the energy barrier between the perovskite active layer and the electrodes for the effective extraction and transportation of photogenerated holes and electrons from the perovskite layer to their respective electrodes. [45,50,163] Thus, charge transport layers help to enhance the electrical contact at the perovskite layer-electrode interface, which improves charge extraction, transportation, and collection efficiency. The charge transport layers selectively allow the transportation of a specific type of charge, i.e., holes for the HTL and electrons for the ETL, while blocking the other type, as well as protecting the perovskite layer from moisture or air penetration, thereby improving device efficiency and stability.…”

Section: Charge Transport Layersmentioning

confidence: 99%

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

Muchuweni

Martincigh

Nyamori

2021

Adv Energy and Sustain Res

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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 ).

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Section: Active Layermentioning

confidence: 99%

Section: Charge Transport Layersmentioning

confidence: 99%

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

Muchuweni

Martincigh

Nyamori

2021

Adv Energy and Sustain Res

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“…has shown that adding RGO to spiro‐OMeTAD could prevent the Li + from migrating to the surface and reacting with H 2 O. [ 60 ] Furthermore, the formation of colossal pinholes, or cavities in spiro‐OMeTAD/perovskite film caused by Li + migration were prevented, which significantly reduced the channels of water and oxygen entering into the device. The stability results in this chapter are summarized in Table 1 .…”

Section: Ion Migration Blockingmentioning

confidence: 99%

The Application of Graphene Derivatives in Perovskite Solar Cells

Cui

et al. 2020

Small Methods

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traditional power generation methods such as coal and natural gas due to the low-cost raw materials and relatively simple structures of PSCs. [14,15] Both the high efficiency and low cost make PSCs a promising candidate to realize commercialization. Currently, to further improve the performance of PSCs and accelerate the commercialization progress, there are still several challenges to be overcome. For example, the ion migration caused by weak Coulomb force in perovskite lattice is considered to be detrimental to the operational stability. [16-18] In addition, the energy loss originated from the nonradiative recombination limits the open-circuit voltage (V OC) of PSCs. [19,20] Graphene is a 2D and chemically stable material with a hexagonal honeycomb structure composed of carbon atoms, which make itself and their derivatives have multiple applications at interfaces or in functional layers of PSCs (Figure 1). [21,22] For example, the lattice parameter of graphene is 0.246 nm, which is smaller than the radius of I − (0.412 nm). [23] Therefore, it is an ideal material to block the ion migration in PSCs and improve the stability under working conditions. Furthermore, graphene derivatives have numerous derivatives with rich functional groups and adjustable band gaps, which can passivate the specific defect states by rational molecule design and therefore optimize the charge transport in PSCs and reduce the charge recombination. In addition, graphene materials have also been applied in flexible and translucent PSCs because of their semiconductor properties and foldable and transparent inherent natures. [24-26] In this paper, we introduce the history and preparation methods of graphene materials, such as the chemical vapor deposition (CVD) and oxidation-reduction methods. Then, the applications of graphene and its derivatives in PSCs are reviewed, including defect passivation, ion migration blocking, and charge transport optimization. We also summarize the progress of graphene as electrode materials in semitransparent and flexible devices. Finally, the challenges and prospects of the application of graphene materials in PSCs are proposed. 2. Graphene and Its Derivatives Carbon elements are rich in allotropes, [22] such as the 3D graphite and diamond, the 0D fullerenes (C 60) and 1D carbon Perovskite solar cells (PSCs) have attracted much attention due to their high efficiency and low manufacturing cost. However, the defects in perovskite films and the instability issue caused by ion migration limit the further improvement of its efficiency and stability. Graphene and its derivatives are potential materials to solve these problems due to their rich functional groups, environmental stability and compactness, which triggered extensive researches in recent years. In this paper, the development and preparation methods of graphene materials are summarized and then their applications in PSCs are reviewed, with particular emphasis on their function of blocking ion migration.

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“…Previous study revealed that CsPbI 2 Br PSCs using doped 2,2ʹ,7,7ʹ-tetrakis(N,N-di-p-methoxyphenylamine)-9,9ʹ-spirobifluorene (Spiro-OMeTAD) as a hole-transporting material (HTM) showed much lower stability than that of a pure CsPbI 2 Br film under the same conditions [16]. Further studies indicated that the lithium salt contained in Spiro-OMeTAD is hygroscopic, which exacerbates device instability [16,[19][20][21][22]. Therefore, water should be excluded from the whole device fabrication process, including the introduction of the charge-transporting layer, to avoid the undesired phase degradation of α-CsPbI 2 Br.…”

Section: Introductionmentioning

confidence: 99%

“…Dopants such as lithium salts have been widely introduced into organic HTMs to improve their hole mobility. However, most of these additives are hygroscopic [21][22][23]. Therefore, inorganic HTMs may have advantages over their organic counterparts for assembling PSCs based on CsPbI 2 Br [24][25][26][27][28][29].…”

Section: Introductionmentioning

confidence: 99%

Phase degradation of all-inorganic perovskite CsPbI2Br films induced by a p-type CuI granular capping layer

Zhu

Feng

et al. 2020

Sci. China Mater.

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It is necessary to evaluate the interactions between the different functional layers in optoelectronic devices to optimize device performance. Recently, the I-rich allinorganic perovskite CsPbI 2 Br has attracted tremendous attention for use in solar cell applications because of its suitable band gap and favorable photo and thermal stabilities. It has been reported that the undesirable phase degradation of the photoactive α phase CsPbI 2 Br to the non-perovskite δ phase could be triggered by high humidity. To obtain stable devices, it is thus important to protect CsPbI 2 Br from moisture. In this paper, CuI, a non-hygroscopic p-type hole-transporting material, is found to induce the phase degradation of α-CsPbI 2 Br to the δ-CsPbI 2 Br. The rate and extent of phase degradation of CsPbI 2 Br are closely associated with the heating temperature and coverage of a CuI granular capping layer. This discovery is different from the widely reported water-induced phase degradation of CsPbI 2 Br. Our work highlights the importance of careful selection of hole-transporting materials during the processing of I-rich all-inorganic CsPbX 3 (X=Br, I) perovskites to realize high-performance optoelectronic devices.

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Improving and Stabilizing Perovskite Solar Cells with Incorporation of Graphene in the Spiro-OMeTAD Layer: Suppressed Li Ions Migration and Improved Charge Extraction

Cited by 34 publications

References 52 publications

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

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

The Application of Graphene Derivatives in Perovskite Solar Cells

Phase degradation of all-inorganic perovskite CsPbI2Br films induced by a p-type CuI granular capping layer

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