ORCID Profile
0000-0001-6923-8015
Current Organisations
University of Cambridge
,
UNSW Sydney
,
Diamond Light Source
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Publisher: Royal Society of Chemistry (RSC)
Date: 2020
DOI: 10.1039/D0TA04863A
Abstract: Three kesterite thin-film solar cells, Cu 2 ZnSnSe 4 (CZTSe), Cu 2 ZnSn(S,Se) 4 (CZTSSe), and Cu 2 ZnSnS 4 (CZTS), and based on low light intensity measurements, examined the possibility of using kesterite devices for indoor applications.
Publisher: American Scientific Publishers
Date: 12-12-2018
Publisher: Informa UK Limited
Date: 02-01-2016
Publisher: Elsevier BV
Date: 04-2019
Publisher: Wiley
Date: 12-09-2021
Abstract: Organometal perovskite single crystals have been recognized as a promising platform for high‐performance optoelectronic devices, featuring high crystallinity and stability. However, a high trap density and structural nonuniformity at the surface have been major barriers to the progress of single crystal‐based optoelectronic devices. Here, the formation of a unique nanoisland structure is reported at the surface of the facet‐controlled cuboid MAPbI 3 (MA = CH 3 NH 3 + ) single crystals through a cation interdiffusion process enabled by energetically vaporized CsI. The interdiffusion of mobile ions between the bulk and the surface is triggered by thermally activated CsI vapor, which reconstructs the surface that is rich in MA and CsI with reduced dangling bonds. Simultaneously, an array of Cs‐Pb‐rich nanoislands is constructed on the surface of the MAPbI 3 single crystals. This newly reconstructed nanoisland surface enhances the light absorbance over 50% and increases the charge carrier mobility from 56 to 93 cm 2 V −1 s −1 . As confirmed by Kelvin probe force microscopy, the nanoislands form a gradient band bending that prevents recombination of excess carriers, and thus, enhances lateral carrier transport properties. This unique engineering of the single crystal surface provides a pathway towards developing high‐quality perovskite single‐crystal surface for optoelectronic applications.
Publisher: Wiley
Date: 16-02-2021
Publisher: Elsevier BV
Date: 12-2018
Publisher: Wiley
Date: 28-07-2023
Abstract: Long‐chain organic halide salts are widely used in perovskite‐based optoelectronic devices for surface passivation owing to their capability to interact with the surface defects of perovskites. Here, aluminum oxide (AlO x ) is introduced via atomic layer deposition onto octylammonium iodide (OAI) to exploit the benefits of organic halide salts without generating undesired defects. The devices incorporating AlO x on OAI‐treated perovskite (OAI/AlO x ) show enhancement in both device performance and photo‐stability compared to those with only treatment. A diffusion of aluminum from AlO x into the perovskite through surface characterization contributes to a uniform photo‐generated carrier transport in both the surface and the bulk of the perovskite absorber. In addition, it is revealed that light‐induced two‐dimensional perovskite formation on OAI/AlO x . This may be ascribed to preventing the loss of OA cations due to the presence of AlO x , leading to a decrease in the number of iodine anions which suppresses the light‐induced degradation of corresponding devices. Consequently, the devices show over 24% efficiency and retain their efficiency over 1000 hours under continuous light illumination.
Publisher: Elsevier BV
Date: 09-2019
Publisher: American Chemical Society (ACS)
Date: 04-01-2021
Publisher: American Chemical Society (ACS)
Date: 14-03-2022
Publisher: Elsevier BV
Date: 12-2018
Publisher: Wiley
Date: 08-12-2021
Abstract: The use of inexpensive, highly efficient, and long‐term stable hole‐transporting layers (HTLs) while facilitating the fabrication process has become a critical issue for PSC commercialization. Among organic HTLs, copper phthalocyanine (CuPc) has been increasingly studied owing to its low cost and excellent thermal stability. Nevertheless, CuPc has a low energy level in the conduction band, resulting in low efficiency due to a poor electron barrier. In this study, an efficient and stable PSC is fabricated by combining CuPc with an ultrathin poly(methyl methacrylate) (PMMA) interlayer, which is deposited on a [(FAPbI 3 ) 0.95 (MAPbBr 3 ) 0.05 ] absorption layer (here, FAPbI 3 and MAPbBr 3 denote formamidinium lead triiodide and methylammonium lead tribromide, respectively). PMMA in perovskite has been found to reduce perovskite surface defects and series resistance as well as the electronic barrier to HTL. The optimum concentration of PMMA allows for the fabrication of the PSC with a PCE of 21.3%, which is the highest PCE for PSCs featuring metal phthalocyanines as the HTL reported to date. The stability of the encapsulated PSC exceeds 80% after 760 h at 85 °C under 85% RH conditions.
Publisher: Elsevier BV
Date: 2021
Publisher: American Chemical Society (ACS)
Date: 24-05-2019
Publisher: Springer Science and Business Media LLC
Date: 08-12-2022
Publisher: Elsevier BV
Date: 07-2017
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C5RA21087A
Abstract: We demonstrate the julolidine moiety is an excellent electron donating building block for developing interfacial modifiers to improve the ZnO surface properties in inverted polymer solar cells.
Publisher: American Chemical Society (ACS)
Date: 02-05-2022
Abstract: Copper (Cu) is present not only in the electrode for inverted-structure halide perovskite solar cells (PSCs) but also in transport layers such as copper iodide (CuI), copper thiocyanate (CuSCN), and copper phthalocyanine (CuPc) alternatives to spiro-OMeTAD due to their improved thermal stability. While Cu or Cu-incorporated materials have been effectively utilized in halide perovskites, there is a lack of thorough investigation on the direct reaction between Cu and a perovskite under thermal stress. In this study, we investigated the thermal reaction between Cu and a perovskite as well as the degradation mechanism by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Kelvin probe force microscopy (KPFM). The results show that high temperatures of 100 °C induce Cu to be incorporated into the perovskite lattice by forming "Cu-rich yet organic A-site-poor" perovskites, (Cu
Publisher: Springer Science and Business Media LLC
Date: 23-06-2022
DOI: 10.1038/S41699-022-00317-5
Abstract: Greater stability of low-dimensional halide perovskites as opposed to their three-dimensional counterparts, alongside their high extinction coefficient and thus excellent emission properties, have made them popular candidates for optoelectronic applications. Topological edges are found in two-dimensional perovskites that show distinct electronic properties. In this work, using Kelvin Probe Force Microscopy, performed on butylammonium lead bromide (BA 2 PbBr 4 ) single crystals with optical bandgap of ~413 nm, we elucidate the electronic response of the edges and their potential impact on photodetector devices. We show that the charge-carriers are accumulated at the edges, increasing with the edge height. Wavelength-dependent surface photovoltage (SPV) measurements reveal that multiple sub-bandgap states exist in BA 2 PbBr 4 . As the edge height increases, the SPV litude at the edges reduces slightly more as compared to the adjacent regions, known as terraces, indicating relatively less reduction in band-bending at the surface due possibly to increased de-population of electrons from sub-bandgap states in the upper bandgap half. The existence of sub-bandgap states is further confirmed by the observation of below-bandgap emission (absorption) peaks characterised by spectral photoluminescence and photothermal deflection spectroscopy measurements. Finally, we fabricated a photodetector using a millimetre size BA 2 PbBr 4 single crystal. Noticeable broadband photodetection response was observed in the sub-bandgap regions under green and red illumination, which is attributed to the existence of sub-bandgap states. Our observations suggest edge-height dependence of charge-carrier behaviour in BA 2 PbBr 4 single crystals, a potential pathway that can be exploited for efficient broadband photodetector fabrication.
Publisher: Elsevier BV
Date: 12-2020
Publisher: Wiley
Date: 28-04-2022
Abstract: Charge carrier transport in materials is of essential importance for photovoltaic and photonic applications. Here, the authors demonstrate a controllable acceleration or deceleration of charge carrier transport in specially structured metal‐alloy perovskite (MACs)PbI 3 (MA= CH 3 NH 3 ) single‐crystals with a gradient composition of CsPbI 3 /(MA 1− x Cs x )PbI 3 /MAPbI 3 . Depending on the Cs‐cation distribution in the structure and therefore the energy band alignment, two different effects are demonstrated: i) significant acceleration of electron transport across the depth driven by the gradient band alignment and suppression of electron–hole recombination, benefiting for photovoltaic and detector applications and ii) decelerated electron transport and thus improved radiative carrier recombination and emission efficiency, highly beneficial for light and display applications. At the same time, the top Cs‐layer results in hole localization in the top layer and surface passivation. This controllable acceleration and deceleration of electron transport is critical for various applications in which efficient electron–hole separation and suppressed nonradiative electron–hole recombination is demanded.
Publisher: Royal Society of Chemistry (RSC)
Date: 2022
DOI: 10.1039/D1TA10638D
Abstract: Solar cells made from Cu 2 ZnSn(S,Se) 4 (CZTS)-derived materials have been widely studied for their favourable material properties utilized in photovoltaic energy conversion.
Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C9RA01107B
Abstract: A method for enhancing the moisture barrier property of polydimethylsiloxane (PDMS) polymer films is proposed. This is achieved by filling the PDMS free volume with aluminum oxide (AlO x ).
Publisher: American Chemical Society (ACS)
Date: 30-11-2021
Location: Korea, Republic of
Location: Korea, Republic of
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: No location found
No related grants have been discovered for Eunyoung Choi.