Publications by authors named "Sung-Nam Kwon"

The interface between NiO and perovskite in inverted perovskite solar cells (PSCs) is a major factor that can limit device performance due to defects and inappropriate redox reactions, which cause nonradiative recombination and decrease in open-circuit voltage (VOC). In the present study, a novel approach is used for the first time, where an amino acid (glycine (Gly), alanine (Ala), and aminobutyric acid (ABA))-complexed NiO are used as interface modifiers to eliminate defect sites and hydroxyl groups from the surface of NiO. The Ala-complexed NiO suppresses interfacial non-radiative recombination, improves the perovskite layer quality and better energy band alignment with the perovskite, resulting in improved charge transfer and reduced recombination.

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For p-i-n perovskite solar cells (PSCs), nickel oxide (NiO) hole transport layers (HTLs) are the preferred interfacial layer due to their low cost, high mobility, high transmittance, and stability. However, the redox reaction between the Ni and hydroxyl groups in the NiO and perovskite layer leads to oxidized CHNH and reacts with PbI in the perovskite, resulting in a large number of non-radiative recombination sites. Among various transition metals, an ultra-thin zinc nitride (ZnN) layer on the NiO surface is chosen to prevent these redox reactions and interfacial issues using a simple solution process at low temperatures.

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Article Synopsis
  • - The study focuses on perovskite solar cells (PSCs) which have efficiencies over 26% but struggle with defects and ion migration at grain boundaries, limiting their performance.
  • - A new approach called mixed ammonium ligands passivation strategy (MAPS) was tested, using a combination of n-octylammonium iodide (OAI) and 1,3-diaminopropane (DAP) to reduce defects and enhance efficiency and stability.
  • - The MAPS method resulted in significant improvements, achieving peak power conversion efficiencies of 21.29% and 19.59% for opaque and submodules respectively, while maintaining high performance even after extended exposure to harsh conditions.
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Perovskite solar cells (PSCs) emerged as potential photovoltaic energy-generating devices developing in recent years because of their excellent photovoltaic properties and ease of processing. However, PSCs are still reporting efficiencies much lower than their theoretical limits owing to various losses caused by the charge transport layer and the perovskite. In this regard, herein, an interface engineering strategy using functional molecules and chemical bridges was applied to reduce the loss of the heterojunction electron transport layer.

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Article Synopsis
  • - Perovskite solar cells (PSCs) are quickly improving and are nearly as effective as traditional silicon solar cells, with a special focus on their use for semi-transparent applications.
  • - Semi-transparent PSCs (ST-PSCs) have unique properties that make them suitable for tandem solar cells and building-integrated photovoltaics, but achieving a balance between light transmittance and efficiency poses challenges.
  • - Current research is exploring innovative solutions such as tuning the band-gap, enhancing charge transport layers, and developing microstructured designs to optimize ST-PSCs, while also addressing their future potential and ongoing challenges.
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Perovskite photovoltaics (PePVs) tend to suffer from a high density of defects that restrict the device in terms of performances and stability. Therefore, defect passivation and film-quality improvement of perovskite active layers are crucial for high-performance PePVs. In this work, 2-chloroethyl acrylate (CEA) with C═O and -Cl groups in CsFAMAPb (IBr) precursor solutions is introduced as a novel bifunctional additive to act as both a defect passivator and perovskite-growth controller.

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PCBM is commonly used in perovskite solar cells (PSC) as the electron transport material (ETM). However, PCBM film has various disadvantages, such as its low coverage or the many pinholes that appear due to its aggregation behavior. These faults may lead to undesirable direct contact between the metal cathode and perovskite film, which could result in charge recombination at the perovskite/metal interface.

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Article Synopsis
  • This article presents detailed images from field emission scanning electron microscopy (FE-SEM) and energy dispersive X-ray spectroscopy (EDS) of polyurethane-silver nanoparticles/graphene nanoplatelets composite fibers made through a wet-spinning process.
  • It also discusses how the microstructure of these composite fibers changes when subjected to different heat treatment temperatures.
  • The data supports findings in a related research article focused on creating stretchable and electrically conductive fibers using the same materials and methods.
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