Doping strategies for small molecule organic hole-transport materials: impacts on perovskite solar cell performance and stability

Schloemer, Tracy H.; Christians, Jeffrey A.; Luther, Joseph M.; Sellinger, Alan

doi:10.1039/c8sc05284k

Cited by 317 publications

(272 citation statements)

References 176 publications

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“…[66][67][68] 2,2,7,7-tetrakis(N,N-di-p-methoxyphenylamine)-9,9 0 -spirobifluorene (spiro-OMeTAD) is commonly used as a HTM in gold-based PSCs. 69 It needs to be doped with lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), a hygroscopic and deliquescent salt that allows the penetration of water molecules, leading to the decomposition of the perovskite. 70,71 Luckily, perovskite materials show a large carrier path and PSCs can also work without the HTM.…”

Section: Federico Bellamentioning

confidence: 99%

Carbon-based materials for stable, cheaper and large-scale processable perovskite solar cells

Fagiolari

Bella

2019

Energy Environ. Sci.

258

188

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Almost ten years after their first use in the photovoltaic (PV) field, perovskite solar cells (PSCs) are now hybrid devices that, in addition to having reached silicon performance, can accelerate the energy transition and boost the use of abundant elements for their manufacturing process. However, noble metals (in particular gold) represent the most typically used sources for back electrode fabrication, and this issue has been intensively considered by the research community in the last five years. This review shows how the most promising solution, considering also the need to develop a large-scale production process, is based on the use of carbon-based materials for the preparation of back electrodes. Graphite, carbon black, graphene and carbon nanotubes (CNTs) have been proposed, functionalized and characterized, leading to laboratory-scale solar cells and modules capable of providing excellent efficiencies and ensuring stability greater than those of gold-based devices. Strengthened by these results and its hydrophobizing properties, carbon has also started to be used as an electron transporting material (ETM), with excellent results on both rigid and flexible substrates. This review discusses the major advances and the updated state-of-the-art in the carbon-based PSC scenario, keeping a solid trajectory where the accessibility, low cost, high electrical conductivity, chemical stability and controllable porosity of carbon are highlighted and exploited in the design of upscalable hybrid solar cells. Broader contextToday, more than 75% of the world energy demand is met by traditional, non-sustainable energy resources, mainly based on coal, natural gas and oil. Photovoltaics represents a concrete action to mitigate fossil fuel consumption, and among all the developed solar cells, perovskite-based ones have shown the highest increase in terms of efficiency (currently above 25%). Halide perovskites, as a family of new-generation semiconductor materials, are also exploitable for light-emitting devices, photodetectors and memristors, but their use in photovoltaics gives rise to outstanding performances. Here, photogenerated charges pass through electron/hole transporting materials and are transferred to the external circuit by front and back electrodes. While the front electrode is a common conductive glass, many issues are now under study concerning the back electrode, traditionally made of gold. Indeed, replacing this expensive metal with a much cheaper alternative is vital for realizing affordable solar technologies. Carbon, in its multiple forms, represents the winning solution and the scientific community has recently shown its large scale processability, its power as a stability booster and some interesting effects at the perovskite/electrode interface. This review shows how carbon is becoming the winning ingredient for the scaling up and worldwide diffusion of perovskite solar cells.

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Section: Federico Bellamentioning

confidence: 99%

Carbon-based materials for stable, cheaper and large-scale processable perovskite solar cells

Fagiolari

Bella

2019

Energy Environ. Sci.

258

188

View full text Add to dashboard Cite

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“…This rapid progress is due to the excellent optoelectronic properties of the common 3D perovskite with ABX 3 structure [typically A = CH 3 NH 3 + (MA + ), CH(NH 2 ) 2 + (FA + ), Cs + ; B = Pb 2+ , Sn 2+ ; X = I − , Br − , Cl − ], [ 1,2 ] and to the unremitting optimization of charge‐selective contacts. [ 3,4 ] However, long‐term stability still remains a bottleneck for PSC commercialization. The hydrophilic nature of MA + and FA + , [ 5 ] the low phase stability under elevated temperature, [ 6 ] and the low activation energy for ion migration, [ 7 ] all contribute to the poor PSC stability.…”

Section: Introductionmentioning

confidence: 99%

Energetics and Energy Loss in 2D Ruddlesden–Popper Perovskite Solar Cells

Yang

Xiong

Song

et al. 2020

Advanced Energy Materials

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2D Ruddlesden–Popper perovskites (RPPs) are emerging as potential challengers to their 3D counterpart due to superior stability and competitive efficiency. However, the fundamental questions on energetics of the 2D RPPs are not well understood. Here, the energetics at (PEA)2(MA)n−1PbnI3n+1/[6,6]‐phenyl‐C61‐butyric acid methyl ester (PCBM) interfaces with varying n values of 1, 3, 5, 40, and ∞ are systematically investigated. It is found that n–n junctions form at the 2D RPP interfaces (n = 3, 5, and 40), instead of p–n junctions in the pure 2D and 3D scenarios (n = 1 and ∞). The potential gradient across phenethylammonium iodide ligands that significantly decreases surface work function, promotes separation of the photogenerated charge carriers with electron transferring from perovskite crystal to ligand at the interface, reducing charge recombination, which contributes to the smallest energy loss and the highest open‐circuit voltage (Voc) in the perovskite solar cells (PSCs) based on the 2D RPP (n = 5)/PCBM. The mechanism is further verified by inserting a thin 2D RPP capping layer between pure 3D perovskite and PCBM in PSCs, causing the Voc to evidently increase by 94 mV. Capacitance–voltage measurements with Mott–Schottky analysis demonstrate that such Voc improvement is attributed to the enhanced potential at the interface.

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“…13,14 Another approach to reduce the energy mismatch between a semiconductor and an electrode is to increase the charge-carrier density in the organic semiconductor through doping. [15][16][17] In p-i-n perovskite solar cells employing fullerene ETLs, typically C 60 or 1-[3-(methoxycarbonyl)propyl]-1-phenyl-[6.6]C 61 (PCBM), ohmic injection is ensured by depositing a thin interlayer between the ETL and the electrode. This includes different molecules such as 1,3,5-tri(m-pyrid-3-yl-phenyl)benzene (TmPyPB) 18 or (2-(1,10-phenanthrolin-3-yl)naphth-6-yl) diphenylphosphine oxide (DPO), 19 inorganic salts such as LiF, 20 or n-type metal oxides.…”

Section: Introductionmentioning

confidence: 99%

High voltage vacuum-processed perovskite solar cells with organic semiconducting interlayers

et al. 2020

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Doping strategies for small molecule organic hole-transport materials: impacts on perovskite solar cell performance and stability

Abstract: Dopants for small molecule-based organic hole-transport layers impact both perovskite solar cells initial performance and long-term stability.

Cited by 317 publications

References 176 publications

Carbon-based materials for stable, cheaper and large-scale processable perovskite solar cells

Carbon-based materials for stable, cheaper and large-scale processable perovskite solar cells

Energetics and Energy Loss in 2D Ruddlesden–Popper Perovskite Solar Cells

High voltage vacuum-processed perovskite solar cells with organic semiconducting interlayers

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