Hyesung Park

In this work, organic photovoltaics (OPV) with graphene electrodes are constructed where the effect of graphene morphology, hole transporting layers (HTL), and counter electrodes are presented. Instead of the conventional poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate) PEDOT:PSS HTL, an alternative transition metal oxide HTL (molybdenum oxide (MoO(3))) is investigated to address the issue of surface immiscibility between graphene and PEDOT:PSS. Graphene films considered here are synthesi

In this work graphene sheets grown by chemical vapor deposition (CVD) with controlled numbers of layers were used as transparent electrodes in organic photovoltaic (OPV) devices. It was found that for devices with pristine graphene electrodes, the power conversion efficiency (PCE) is comparable to their counterparts with indium tin oxide (ITO) electrodes. Nevertheless, the chances for failure in OPVs with pristine graphene electrodes are higher than for those with ITO electrodes, due to the surf

Advancements in the field of flexible high-efficiency solar cells and other optoelectronic devices will strongly depend on the development of electrode materials with good conductivity and flexibility. To address chemical and mechanical instability of currently used indium tin oxide (ITO), graphene has been suggested as a promising flexible transparent electrode but challenges remain in achieving high efficiency of graphene-based polymer solar cells (PSCs) compared to their ITO-based counterpart

Abstract The operating principle of conventional water electrolysis using heterogenous catalysts has been primarily focused on the unidirectional charge transfer within the heterostructure. Herein, multidirectional charge transfer concept has been adopted within heterostructured catalysts to develop an efficient and robust bifunctional water electrolysis catalyst, which comprises perovskite oxides (La 0.5 Sr 0.5 CoO 3– δ , LSC) and potassium ion-bonded MoSe 2 (K-MoSe 2 ). The complementary charg

Growth of semiconducting nanostructures on graphene would open up opportunities for the development of flexible optoelectronic devices, but challenges remain in preserving the structural and electrical properties of graphene during this process. We demonstrate growth of highly uniform and well-aligned ZnO nanowire arrays on graphene by modifying the graphene surface with conductive polymer interlayers. On the basis of this structure, we then demonstrate graphene cathode-based hybrid solar cells

Considering the potential applications of all-polymer solar cells (all-PSCs) as wearable power generators, there is an urgent need to develop photoactive layers that possess intrinsic mechanical endurance, while maintaining a high power-conversion efficiency (PCE).Herein a strategy is demonstrated to simultaneously control the intercalation behavior and nanocrystallite size in the polymer-polymer blend by using a newly developed, high-viscosity polymeric additive, poly(dimethylsiloxane-co-methyl

Abstract Developing efficient bifunctional catalysts for overall water splitting that are earth-abundant, cost-effective, and durable is of considerable importance from the practical perspective to mitigate the issues associated with precious metal-based catalysts. Herein, we introduce a heterostructure comprising perovskite oxides (La 0.5 Sr 0.5 CoO 3– δ ) and molybdenum diselenide (MoSe 2 ) as an electrochemical catalyst for overall water electrolysis. Interestingly, formation of the heterostr

Graphene as an atom-thick carbon material is promising for the detection of gaseous molecules owing to extremely high surface-to-volume ratio. However, the majority of graphene-based gas sensors, prepared by chemical vapor deposition (CVD), have suffered from non-uniformity in their responses. Such a high sensor-to-sensor variation in responses has not been systematically studied, limiting application of graphene gas sensors. Here we report processes that lead to a highly sensitive and uniform g

Abstract The crystalline phase of layered transition metal dichalcogenides (TMDs) directly determines their material property. The most thermodynamically stable phase structures in TMDs are the semiconducting 2H and metastable metallic 1T phases. To overcome the low phase purity and instability of 1T‐TMDs, which limits the utilization of their intrinsic properties, various synthesis strategies for 1T‐TMDs have been proposed in phase‐engineering studies. Herein, a facile and scalable synthesis of

A vacuum-deposited highly ordered butylammonium-based Ruddlesden–Popper phase perovskite is introduced as a passivation layer for highly efficient and stable inverted perovskite solar cells.

Water electrolysis is emerging as a promising renewable-energy technology for the green production of hydrogen, which is a representative and reliable clean energy source. From economical and industrial perspectives, the development of earth-abundant non-noble metal-based and bifunctional catalysts, which can simultaneously exhibit high catalytic activities and stabilities for both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER), is critical; however, to date, these

Introduction of an n-type macromolecular additive (P(NDI2OD-T2) polymer) in organic solar cells brings significant improvements in power conversion efficiency along with robust thermal stability.

Metal-based transparent conductive electrodes (TCEs) are attractive candidates for application in indium tin oxide (ITO)-free solar cells due to their excellent electrical conductivity and cost effectiveness. In perovskite solar cells (PSCs), metal-induced degradation with the perovskite layer leads to various detrimental effects, deteriorating the device performance and stability. Here, we introduce a novel flexible hybrid TCE consisting of a Cu grid-embedded polyimide film and a graphene cappi

Chemical vapor deposition (CVD) using liquid-phase precursors has emerged as a viable technique for synthesizing uniform large-area transition metal dichalcogenide (TMD) thin films. However, the liquid-phase precursor-assisted growth process typically suffers from small-sized grains and unreacted transition metal precursor remainders, resulting in lower-quality TMDs. Moreover, synthesizing large-area TMD films with a monolayer thickness is also quite challenging. Herein, we successfully synthesi