154 research outputs found
Doping Strategies for Small Molecule Organic Hole-transport Materials: Impacts on Perovskite Solar Cell Performance and Stability
Hybrid organic/inorganic perovskite solar cells (PSCs) have dramatically changed the landscape of the solar research community over the past decade, but \u3e25 year stability is likely required if they are to make the same impact in commercial photovoltaics and power generation more broadly. While every layer of a PSC has been shown to impact its durability in power output, the hole-transport layer (HTL) is critical for several reasons: (1) it is in direct contact with the perovskite layer, (2) it often contains mobile ions, like Li+ â which in this case are hygroscopic, and (3) it usually has the lowest thermal stability of all layers in the stack. Therefore, HTL engineering is one method with a high return on investment for PSC stability and lifetime. Research has progressed in understanding design rules for small organic molecule hole-transport materials, yet, when implemented into devices, the same dopants, bis(trifluoromethane)sulfonimide lithium salt (LiTFSI) and tris(2-(1H-pyrazol-1-yl)-4-tert-butylpyridine)cobalt(III) tri[bis(trifluoromethane)sulfonimide] (FK209), are nearly always required for improved charge-transport properties (e.g., increased hole mobility and conductivity). The dopants are notable because they too have been shown to negatively impact PSC stability and lifetime. In response, new research has targeted alternative dopants to bypass these negative effects and provide greater functionality. In this review, we focus on dopant fundamentals, alternative doping strategies for organic small molecule HTL in PSC, and imminent research needs with regard to dopant development for the realization of reliable, long-lasting electricity generation via PSCs
Assessing health and environmental impacts of solvents for producing perovskite solar cells
Halide perovskites are poised as a game-changing semiconductor system with diverse applications in optoelectronics. Industrial
entities aim to commercialize perovskite technologies because of high performance but also because this type of semiconductor
can be processed from solution, a feature enabling low cost and fast production. Here, we analyse the health and environmental
impacts of eight solvents commonly used in perovskite processing. We consider first- and higher-order ramifications of each
solvent on an industrial scale such as solvent production, use/removal, emissions and potential end-of-life treatments. Further,
we consider the energy of evaporation for each solvent, air emission, condensation and subsequent incineration, reuse or
distillation for solvent recycling, and apply a full end-of-life analysis. For human health impact, we use the âUSEtoxâ method but
also consider toxicity data beyond carcinogenic classifications. We find that dimethyl sulfoxide has the lowest total impact,
by being the most environmentally friendly and least deleterious to human health of the solvents considered. The analysis of
the effects of these solvents on human health and the environment provides guidance for sustainable development of this new
technology
CsIâAntisolvent Adduct Formation in AllâInorganic Metal Halide Perovskites
The excellent optoelectronic properties demonstrated by hybrid organic/inorganic metal halide perovskites are all predicated on precisely controlling the exact nucleation and crystallization dynamics that occur during film formation. In general, highâperformance thin films are obtained by a method commonly called solvent engineering (or antisolvent quench) processing. The solvent engineering method removes excess solvent, but importantly leaves behind solvent that forms chemical adducts with the leadâhalide precursor salts. These adductâbased precursor phases control nucleation and the growth of the polycrystalline domains. There has not yet been a comprehensive study comparing the various antisolvents used in different perovskite compositions containing cesium. In addition, there have been no reports of solvent engineering for high efficiency in allâinorganic perovskites such as CsPbI3. In this work, inorganic perovskite composition CsPbI3 is specifically targeted and unique adducts formed between CsI and precursor solvents and antisolvents are found that have not been observed for other Aâsite cation salts. These CsI adducts control nucleation more so than the PbI2âdimethyl sulfoxide (DMSO) adduct and demonstrate how the Aâsite plays a significant role in crystallization. The use of methyl acetate (MeOAc) in this solvent engineering approach dictates crystallization through the formation of a CsIâMeOAc adduct and results in solar cells with a power conversion efficiency of 14.4%.It is found that unique adducts form between CsI and dimethyl sulfoxide (DMSO) and certain antisolvents, such as methyl acetate, during film formation of the allâinorganic perovskite CsPbI3. These adducts significantly influence crystallization and the power conversion efficiency of the resulting solar cells.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/154525/1/aenm201903365-sup-0001-SuppMat.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/154525/2/aenm201903365.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/154525/3/aenm201903365_am.pd
CsIâAntisolvent Adduct Formation in AllâInorganic Metal Halide Perovskites
The excellent optoelectronic properties demonstrated by hybrid organic/inorganic metal halide perovskites are all predicated on precisely controlling the exact nucleation and crystallization dynamics that occur during film formation. In general, highâperformance thin films are obtained by a method commonly called solvent engineering (or antisolvent quench) processing. The solvent engineering method removes excess solvent, but importantly leaves behind solvent that forms chemical adducts with the leadâhalide precursor salts. These adductâbased precursor phases control nucleation and the growth of the polycrystalline domains. There has not yet been a comprehensive study comparing the various antisolvents used in different perovskite compositions containing cesium. In addition, there have been no reports of solvent engineering for high efficiency in allâinorganic perovskites such as CsPbI3. In this work, inorganic perovskite composition CsPbI3 is specifically targeted and unique adducts formed between CsI and precursor solvents and antisolvents are found that have not been observed for other Aâsite cation salts. These CsI adducts control nucleation more so than the PbI2âdimethyl sulfoxide (DMSO) adduct and demonstrate how the Aâsite plays a significant role in crystallization. The use of methyl acetate (MeOAc) in this solvent engineering approach dictates crystallization through the formation of a CsIâMeOAc adduct and results in solar cells with a power conversion efficiency of 14.4%.It is found that unique adducts form between CsI and dimethyl sulfoxide (DMSO) and certain antisolvents, such as methyl acetate, during film formation of the allâinorganic perovskite CsPbI3. These adducts significantly influence crystallization and the power conversion efficiency of the resulting solar cells.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/154525/1/aenm201903365-sup-0001-SuppMat.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/154525/2/aenm201903365.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/154525/3/aenm201903365_am.pd
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