Park, Hui Joon

UNLABELLED: In this work, we report on solution-based p-i-n-type planar-structured CH3NH3PbI3 perovskite photovoltaic (PV) cells, in which precrystallized NiO nanoparticles (NPs) without post-treatment are used to form a hole transport layer (HTL). X-ray diffraction and high-resolution transmission electron microscopy showed the crystallinity of the NPs, and atomic force microscopy and scanning electron microscopy confirmed the uniform surfaces of the resultant NiO thin film and the subsequent p

Color filters are indispensable in most color display applications. In most cases, they are chemical pigment-based filters, which produce a particular color by absorbing its complementary color, and the absorbed energy is totally wasted. If the absorbed and wasted energy can be utilized, e.g., to generate electricity, innovative energy-efficient electronic media could be envisioned. Here we show photonic nanostructures incorporated with photovoltaics capable of producing desirable colors in the

A new fabrication method for polymer solar cells that can produce optimized vertical distribution of components is reported. The favorable donor–acceptor morphology showing a well-organized photo-induced charge transporting pathway with fine nanodomains and high crystallinity is achieved. This process is also readily scalable to a large-area and high-speed roll-to-roll process without sacrificing high device performances, even without a PEDOT:PSS layer.

Abstract Methoxy‐functionalized triphenylamine‐imidazole derivatives that can simultaneously work as hole transport materials (HTMs) and interface‐modifiers are designed for high‐performance and stable perovskite solar cells (PSCs). Satisfying the fundamental electrical and optical properties as HTMs of p‐i‐n planar PSCs, their energy levels can be further tuned by the number of methoxy units for better alignment with those of perovskite, leading to efficient hole extraction. Moreover, when they

Triarylamine derivatives containing electron donating methoxy units provide outstanding device performance as dopant-free hole transporting materials in inverse type planar heterojunction perovskite solar cells.

In organic hole-transporting material (HTM)-based p-i-n planar perovskite solar cells, which have simple and low-temperature processibility feasible to flexible devices, the incident light has to pass through the HTM before reaching the perovskite layer. Therefore, photo-excited state of organic HTM could become important during the solar cell operation, but this feature has not usually been considered for the HTM design. Here, we prove that enhancing their property at their photo-excited states

An optoelectronic synapse having a multispectral color-discriminating ability is an essential prerequisite to emulate the human retina for realizing a neuromorphic visual system. Several studies based on the three-terminal transistor architecture have shown its feasibility; however, its implementation with a two-terminal memristor architecture, advantageous to achieving high integration density as a simple crossbar array for an ultra-high-resolution vision chip, remains a challenge. Furthermore,

Abstract Gallium arsenide (GaAs) photovoltaic (PV) cells have been widely investigated due to their merits such as thin‐film feasibility, flexibility, and high efficiency. To further increase their performance, a wider bandgap PV structure such as indium gallium phosphide (InGaP) has been integrated in two‐terminal (2T) tandem configuration. However, it increases the overall fabrication cost, complicated tunnel‐junction diode connecting subcells are inevitable, and materials are limited by latti

We present flexible transmissive structural color filters with high-color-purity based on a higher-order resonance suppression by inserting an ultrathin absorbing layer in the middle of a cavity. A 3rd order Fabry-Pérot (F-P) resonance, which exhibits a narrower bandwidth than a fundamental F-P resonance, is used to produce transmissive colors with an improved color purity. The thin absorbing layer is properly placed at a center of the cavity to highly suppress only a 5th order F-P resonance app

We developed simple fabrication methods to effectively transfer the block copolymer nanopatterns to a substrate material. High aspect ratio, sub-20 nm nanopillar and nanohole structures are successfully fabricated in a SiO(2) layer in large area format, and the versatile utilities of these nanostructures as nanoimprint molds are studied. Nanoimprint lithography using these molds makes it possible to easily replicate densely packed block copolymer nanotemplate patterns on arbitrary substrates in

Highly efficient colored perovskite solar cells that exploit localized surface plasmon resonances in ultrathin subwavelength plasmonic nanoresonators are demonstrated. Localized resonances in ultrathin metal nano-strip optical resonators consisting of an array of metallic subwavelength nanowires on a transparent substrate, fabricated by using low-cost nanoimprint lithography over a large area, lead to a sharp peak in a reflection spectrum for distinctive color generation with angle-insensitive p

Organic photovoltaics (OPVs) have been pursued as a next generation power source due to their light weight, thin, flexible, and simple fabrication advantages. Improvements in OPV efficiency have attracted great attention in the past decade. Because the functional layers in OPVs can be dissolved in common solvents, they can be manufactured by eco-friendly and scalable printing or coating technologies. In this review article, the focus is on recent efforts to control nanomorphologies of photoactiv

Organic–inorganic perovskite solar cells (PSCs) have shown tremendous progress from 3.8% power conversion efficiency (PCE) in 2003 to 25.2% in 2020 because of their wide range of light absorption, fast charge separation, long carrier diffusion length, and long carrier lifetime. The optoelectronic characteristics of hole transport material (HTM) and electron transport material (ETM) strongly affect photovoltaic (PV) performance and stability of PSCs. Recently, various inorganic HTMs with high eff

In this review, we summarize recent works on perovskite solar cells with neutral- and multi-colored semitransparency for building-integrated photovoltaics and tandem solar cells. The perovskite solar cells exploiting microstructured arrays of perovskite "islands" and transparent electrodes-the latter of which include thin metallic films, metal nanowires, carbon nanotubes, graphenes, and transparent conductive oxides for achieving optical transparency-are investigated. Moreover, the perovskite so