Showing papers by "Min Jae Ko published in 2020"
94 citations
TL;DR: In this paper, the NiCo2S4 nanoflakes increased the surface area of the composite electrode, thereby increasing its specific capacity from 106.34 Cg−1 to 596.69 C g−1.
94 citations
TL;DR: In this paper, short-chain and hydrophobic phenethylammonium (PEA) cations are incorporated onto CsPbI3-QD surfaces, confirmed by Fourier transform infrared, H nuclear magnetic resonance and density functional theory calculations.
61 citations
01 Oct 2020
33 citations
TL;DR: In this article, the authors summarized inorganic passivating materials and their individual passivation principles and methods and offered a personal perspective for future research trends in the development of passivation strategies through inorganic materials.
Abstract: Surface passivation with organic materials is one of the most effective and popular strategies to improve the stability and efficiency of perovskite solar cells (PSCs). However, the secondary bonding formed between organic molecules and perovskite layers is still not strong enough to protect the perovskite absorber from degradation initialized by oxygen and water attacking at defects. Recently, passivation with inorganic materials has gradually been favored by researchers due to the effectiveness of chemical and mechanical passivation. Lead-containing substances, alkali metal halides, transition elements, oxides, hydrophobic substances, etc. have already been applied to the surface and interfacial passivation of PSCs. These inorganic substances mainly manipulate the nucleation and crystallization process of perovskite absorbers by chemically passivating defects along grain boundaries and surface or forming a mechanically protective layer simultaneously to prevent the penetration of moisture and oxygen, thereby improving the stability and efficiency of the PSCs. Herein, we mainly summarize inorganic passivating materials and their individual passivation principles and methods. Finally, this review offers a personal perspective for future research trends in the development of passivation strategies through inorganic materials.
33 citations
TL;DR: In this article, activated charcoal (AC) is explored as an active spacer material between reduced graphene oxide (rGO) sheets, for the first time, to avoid re-stacking of rGO sheets, which reduces exposed surface area and hinders in electrolyte diffusion.
32 citations
TL;DR: In this paper, an organic-inorganic hybrid perovskite (CH3NH3)PbX3 [X = I−, Cl−, and Br−] materials were evaluated with memristors for resistive switching and synaptic functionalities.
31 citations
TL;DR: In this article, the replacement of native long chain ligands with short-chain ligands, leading to their photovolastic photovoltaics, has been studied in perovskite quantum dots.
Abstract: Advances in surface chemistry and manipulation of CsPbI3 perovskite quantum dots (PQDs) have enabled the replacement of native long-chain ligands with short-chain ligands, leading to their photovol...
28 citations
21 citations
TL;DR: A layer by layer self-assembled uniform coating of ecofriendly red-emissive hollow nitrogen-doped carbon QDs (NR-CQDs), as an efficient energy-down shifting layer to enhance the efficiency of crystalline silicon solar cell (c-Si SC) by coating the energy shifting layer of quantum dots (QDs).
Abstract: Enhancing the efficiency of the crystalline silicon solar cell (c-Si SC) by coating the energy shifting layer with quantum dots (QDs) is a recent approach to efficiently utilize the high-energy spe...
20 citations
TL;DR: In this paper, a highly self-healable polymeric system with enhanced mechanical properties is prepared by blending conventional polyurethane (PU) with functional polyimide (PI).
Abstract: A highly self-healable polymeric system with enhanced mechanical properties is prepared by blending conventional polyurethane (PU) with functional polyimide (PI). PU and PI synthesized in this stud...
TL;DR: A soft contact method to probe the properties of irregularly shaped microscale perovskite crystals by employing a movable liquid metal electrode to form a self-adaptative deformable electrode-perovskites-electrode junction is shown.
Abstract: To reduce the size of optoelectronic devices, it is essential to understand the crystal size effect on the carrier transport through microscale materials. Here, we show a soft contact method to probe the properties of irregularly shaped microscale perovskite crystals by employing a movable liquid metal electrode to form a self-adaptative deformable electrode-perovskite-electrode junction. Accordingly, we demonstrate that (1) the photocurrents of perovskite quantum dot films and microplatelets show profound differences regarding both the on/off ratio and the response time upon light illumination; and (2) small-size perovskite (<50 μm) junctions may show negative differential resistance (NDR) behavior, whereas the NDR phenomenon is absent in large-size perovskite junctions within the same bias regime. Our studies provide a method for studying arbitrary-shaped crystals without mechanical damage, assisting the understanding of the photogenerated carriers transport through microscale crystals.
TL;DR: In this article, a ligand-assisted reprecipitation method was used to synthesize perovskite colloidal nanocrystals for the wide-colour gamut low-cost displays.
TL;DR: In this paper, an Sb2Se3 solar cell with a power conversion efficiency of 2.45% was achieved by controlling the thickness of the photoactive layer and inserting a poly(3-hexylthiophene) hole-transporting layer.
TL;DR: In this paper, the photovoltaic and photoelectrochemical properties of TiO2 NP-only electrodes and multi-layered electrodes comprising NP and NT arrays at the same thickness of 15μm were evaluated.
Abstract: Vertically-aligned TiO2 nanotube (NT) arrays prepared by electrochemical anodization are considered promising alternatives to the conventional nanoparticle (NP)-based electrodes for photovoltaic devices. Recently, such NT arrays have been employed in dye-sensitized solar cells (DSSCs) by transferring them onto NP-based electrodes, to obtain multi-layered nanoelectrodes. Here, we comparatively evaluate the photovoltaic and photoelectrochemical properties of TiO2 NP-only electrodes and multi-layered electrodes comprising NP and NT arrays at the same thickness of 15 μm. Although the multi-layered electrodes have a smaller surface area compared to the NP-only electrodes, they show much higher transmittance. In addition, impedance studies reveal that the multi-layered electrodes have lower charge recombination with the electrolyte as well as enhanced electrolyte diffusion when applied as a photoanode in DSSCs. As a result, the multi-layered electrodes exhibit a photovoltaic conversion efficiency (η = 5.37%) comparable to that of the NP-only electrodes (η = 5.80%), despite 36.6% lower dye loading.
TL;DR: Unlike the conventional self- healing materials, the heterocyclic polyurethane examined in this study shows an outstanding recovery of the mechanical properties after the self-healing process.
Abstract: A functional polyurethane based on the heterocyclic group was synthesized and its self-healing and mechanical properties were examined. To synthesize a heterocyclic polyurethane, a polyol and a heterocyclic compound with di-hydroxyl groups at both ends were blended and the blended solution was reacted with a crosslinker containing multiple isocyanate groups. The heterocyclic polyurethane demonstrates better self-healing efficiency than the conventional polyurethane with no heterocyclic groups. Furthermore, unlike the conventional self-healing materials, the heterocyclic polyurethane examined in this study shows an outstanding recovery of the mechanical properties after the self-healing process. These results are attributed to the unique supramolecular network resulting from the strong hydrogen bonding interaction between the urethane group and the heterocyclic group in the heterocyclic polyurethane matrix.