Yazar "Arora, Neha" seçeneğine göre listele

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    Cyclopentadithiophene-based hole-transporting material for highly stable perovskite solar cells with stabilized efficiencies approaching 21%
    (Amer Chemical Soc., 2020) Akın, Seçkin; Bauer, Michael; Uchida, Ryusuke; Arora, Neha; Jacopin, Gwenole; Liu, Yuhang; Hertel, Dirk
    There is an urge to develop new hole-transporting materials (HTMs) for perovskite solar cells (PSCs), which can yield comparable power conversion efficiencies (PCEs) yet mitigate the issue of stability associated with the state-of-the-art HTM Spiro-MeOTAD. Herein, we designed and prepared C-2v-symmetric spiro-configured HTM-1 comprising a central acridine-cyclopentadithiophene core unit flanked with triarylamine moieties. PSCs containing a 40 nm thin HTM-1 layer for hole extraction yielded a stabilized PCE approaching 21% under standard illumination. Owing to its higher hole mobility (mu(h)) at low electric field, an impressive short-circuit current density (J(SC)) of 24.7 mA cm(-2) and a high fill factor (FF) of 0.77 have been achieved. More importantly, HTM-1-based PSCs presented an excellent long-term operational stability under continuous illumination for 400 h and thermal stability at 80 degrees C, which can be ascribed to its high glass transition temperature of 168 degrees C and superior moisture tolerance. Arguably, the confluence of high performance and remarkable stability will lead to the development of technologically interesting new, stable, and efficient PSCs.
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    Low-cost and highly efficient carbon-based perovskite solar cells exhibiting excellent long-term operational and uv stability
    (Wiley, 2019) Arora, Neha; Dar, M. İbrahim; Akın, Seçkin; Uchida, Ryusuke; Baumeler, Thomas; Liu, Yuhang
    Today's perovskite solar cells (PSCs) mostly use components, such as organic hole conductors or noble metal back contacts, that are very expensive or cause degradation of their photovoltaic performance. For future large-scale deployment of PSCs, these components need to be replaced with cost-effective and robust ones that maintain high efficiency while ascertaining long-term operational stability. Here, a simple and low-cost PSC architecture employing dopant-free TiO2 and CuSCN as the electron and hole conductor, respectively, is introduced while a graphitic carbon layer deposited at room temperature serves as the back electrical contact. The resulting PSCs show efficiencies exceeding 18% under standard AM 1.5 solar illumination and retain approximate to 95% of their initial efficiencies for >2000 h at the maximum power point under full-sun illumination at 60 degrees C. In addition, the CuSCN/carbon-based PSCs exhibit remarkable stability under ultraviolet irradiance for >1000 h while under similar conditions, the standard spiro-MeOTAD/Au based devices degrade severely.
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    New strategies for defect passivation in high-efficiency perovskite solar cells
    (Wiley-V C H Verlag Gmbh) Akın, Seçkin; Arora, Neha; Zakeeruddin, Shaik M.; Graetzel, Michael; Friend, Richard H.; Dar, M. İbrahim
    Lead halide perovskite solar cells now show excellent efficiencies and encouraging levels of stability. Further improvements in performance require better control of the trap states which are considered to be associated with vacancies and defects at crystallite surfaces. Herein, a reflection on the ways in which these traps can be mitigated is presented by improving the quality of the perovskite layer and interfaces in fully assembled device configurations. In this review, the most recent design strategies reported in the literature, which have been explored to tune grain orientation, to passivate defects, and to improve charge-carrier lifetimes, are presented. Specifically, the advances made with single-cation, mixed-cation and/or mixed-halide, and 3D/2D bilayer-based light absorbers are discussed. The interfacial, compositional, and band alignment engineering along with their consequent effects on the open-circuit voltage, power conversion efficiency, and stability are a particular focus.
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    Ultrahydrophobic 3D/2D fluoroarene bilayer-based water-resistant perovskite solar cells with efficiencies exceeding 22%
    (Amer Assoc Advancement Science, 2019) Liu, Yuhang; Akın, Seçkin; Pan, Linfeng; Uchida, Ryusuke; Arora, Neha; Milic, Jovana V.; Hinderhofer, Alexander
    Preventing the degradation of metal perovskite solar cells (PSCs) by humid air poses a substantial challenge for their future deployment. We introduce here a two-dimensional (2D) A(2)PbI(4) perovskite layer using pentafluoro-phenylethylammonium (FEA) as a fluoroarene cation inserted between the 3D light-harvesting perovskite film and the hole-transporting material (HTM). The perfluorinated benzene moiety confers an ultrahydrophobic character to the spacer layer, protecting the perovskite light-harvesting material from ambient moisture while mitigating ionic diffusion in the device. Unsealed 3D/2D PSCs retain 90% of their efficiency during photovoltaic operation for 1000 hours in humid air under simulated sunlight. Remarkably, the 2D layer also enhances interfacial hole extraction, suppressing nonradiative carrier recombination and enabling a power conversion efficiency (PCE) > 22%, the highest reported for 3D/2D architectures. Our new approach provides water-and heat-resistant operationally stable PSCs with a record-level PCE.