Department Of Physics

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    Dual-Functional 3-Acetyl-2,5-dimethylthiophene Additive-Assisted Crystallization Control and Trap State Passivation for High-Performance Perovskite Solar Cells
    (American Chemical Society, 2022-11-25T00:00:00) Saykar, Nilesh G; Iqbal, Muzahir; Pawar, Mahendra; Chavan, Kashinath T; Mahapatra, Santosh K
    Defect-mediated charge recombination and successive degradation mainly lag the performance of perovskite solar cells (PSCs). Insufficiency or evaporation of organic cations leaves behind the undercoordinated Pb2+ions, which act as severe charge recombination centers. Herein, theoretical and experimental insights into crystallization control and defect passivation of MAPbI3perovskite by the dual-functional 3-acetyl-2,5-dimethylthiophene (ADT) molecule are presented. Density functional theory calculations show that both functional groups of ADT possessing different interaction energies could interact with PbI2. The carbonyl group in ADT shows the dominant interaction with Pb2+forming an intermediate product that might decrease the crystallization rate. Further, the coordinate bonding between ADT and uncoordinated Pb2+ions in perovskite leads to defect passivation. The 0.6% ADT-modified PSCs possess an average power conversion efficiency (PCE) of 18.22 � 0.80% and the highest PCE of 19.03%, whereas the pristine PSCs exhibit an average PCE of 16.23 � 1.32% and the highest PCE of 17.47%. Furthermore, the modified PSCs maintain 80% of the initial PCE up to 650 h during storage at ambient conditions (RH = 35 � 5%). The present study shows that the simultaneous crystalization control and defect passivation achieved via an ADT additive engineering approach could be an efficient strategy to enhance the PCE and stability of PSCs. � 2022 American Chemical Society. All rights reserved.
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    A comprehensive review on defect passivation and gradient energy alignment strategies for highly efficient perovskite solar cells
    (IOP Publishing Ltd, 2021-10-07T00:00:00) Saykar, Nilesh G.; Arya, Anil; Mahapatra, S.K.
    Recent advances in photovoltaic devices demonstrate a potential candidature of the lead halide perovskite solar cells (PSCs) to fulfill the all-electric future of the world. Further improvements in efficiency and stability require minimization of non-radiative recombination arising due to the tr ap states created by the vacancies and defects. The device's performance is mostly determined by the perovskite absorber material, which has single-cation, mixed-cation, and/or mixed-halide composition-dependent optoelectronic capabilities. Herein, we present an insight on the state of the art of PSCs, including types of defects, their effects, and remedies of the same. Various design strategies administered to grow highly crystalline perovskite films with low defects at interfaces are described in detail. The inclusion of a few nm thin interlayer between perovskite and charge transport layer (CTL) is an effective way to passivate the defect at the interface. Furthermore, additive engineering is emerging as an excellent strategy to grow the defect-free perovskite by simply adding a polymer, ionic liquids, organic/inorganic salts in precursor solution without precipitating after film formation. The mitigation of charge recombination could be achieved by efficient charge extraction through proper energy alignment of CTLs and absorbers. Notably, we emphasize the interface, additive, and gradient band alignment engineering and resulting improvement in the photocurrent density, photovoltage, power conversion efficiency, and long-term stability. The present review gives complete information about PSCs, starting from the selection of the materials to PSC fabrication, charge carrier dynamics, defects, effects, and remedies. We hope that this summarised information will give a basic understanding of designing new passivation strategies for advancing PSC's present state of the art. � 2021 IOP Publishing Ltd.