Sung‐Yeon Jang 교수

By trapping molecules between two gold electrodes with a temperature difference across them, the junction Seebeck coefficients of 1,4-benzenedithiol (BDT), 4,4'-dibenzenedithiol, and 4,4''-tribenzenedithiol in contact with gold were measured at room temperature to be +8.7 +/- 2.1 microvolts per kelvin (muV/K), +12.9 +/- 2.2 muV/K, and +14.2 +/- 3.2 muV/K, respectively (where the error is the full width half maximum of the statistical distributions). The positive sign unambiguously indicates p-ty

Abstract Herein, this study reports high‐efficiency, low‐temperature ZnO based planar perovskite solar cells (PSCs) with state‐of‐the‐art performance. They are achieved via a strategy that combines dual‐functional self‐assembled monolayer (SAM) modification of ZnO electron accepting layers (EALs) with sequential deposition of perovskite active layers. The SAMs, constructed from newly synthesized molecules with high dipole moments, act both as excellent surface wetting control layers and as elect

We report intrinsically self-healable and stretchable ionic thermoelectric materials, which exhibits excellent ionic figure-of-merit (1.04), with remarkable stretchability (~750%) and autonomous self-healability.

Abstract Polymer solar cells (PSCs) are fabricated using a novel film deposition method, the electrostatic spray (e‐spray) technique. Stable atomization and uniform deposition of the polymer blend by e‐spray are achieved by manipulating the solution concentration, the solvent composition, and the electric field. The performance of PSCs is primarily influenced by the inherent film morphology of the e‐sprayed polymer‐blend active layers, which is significantly different from that of the convention

Colloidal-quantum-dot (CQD) photovoltaic devices are promising candidates for low-cost power sources owing to their low-temperature solution processability and bandgap tunability. A power conversion efficiency (PCE) of >10% is achieved for these devices; however, there are several remaining obstacles to their commercialization, including their high energy loss due to surface trap states and the complexity of the multiple-step CQD-layer-deposition process. Herein, high-efficiency photovoltaic dev

The electrical conductance of a series of thiol-terminated alkanes, (1,6-hexanedithiol (HDT), 1,8-octanedithiol (ODT), and 1,10-decanedithol (DDT)) was measured using a modified scanning tunneling microscope break junction technique. The interpretation of data obtained in this technique is complicated due to multiple effects such as microscopic details of the metal-molecule junctions, superposition of tunneling currents, and conformational changes in the molecules. A new method called the last-s

While perovskite solar cells (PSCs) have emerged as promising low-cost solar power generators, most reported high-performance PSCs employ electron transport layers (ETLs, mainly TiO2) treated at high temperatures (≥450 °C), which may eventually hinder the development of flexible PSCs. Meanwhile, the development of low-temperature processed PSCs (L-PSCs) possessing performance levels comparable to those of high-temperature processed PSCs has actively been reported. In this study, L-PSCs with impr

High-performance solution-processable ZnO thin films for use as electron-transporting layers (ETLs) of inverted-structured polymer solar cells (I-PSCs) are developed via a low-temperature annealing (<200 °C) sol–gel process. The properties of the low-temperature-annealed ZnO (L-ZnO) thin films (used as ETLs) are optimized based on the evaluation of the roles of the internal nanocrystal (NC) orientation and film-surface morphology in charge transport/transfer in I-PSCs. The low-temperature anneal

Abstract In most current state‐of‐the‐art perovskite solar cells (PSCs), high‐temperature (≈500 °C)‐sintered metal oxides are employed as electron‐transporting layers (ETLs). To lower the device processing temperature, the development of low‐temperature‐processable ETL materials (such as solution‐processed ZnO) has received growing attention. However, thus far, the use of solution‐processed ZnO is limited because the reverse decomposition reaction that occurs at ZnO/perovskite interfaces signifi

Herein, we achieved, air-stable low-temperature processed PSC (L-PSC) using alkali-metal modified ZnO ETLs. Using a simple chemical alkali-metal modification method, the surface defects of the ZnO were effectively passivated. As a result, the interfacial decomposition reactions were suppressed, while raising the Fermi energy level and enhancing electron mobility. The improved interfacial charge transfer and internal electric field in the developed L-PSC using K modified ZnO (ZnO-K) exhibited an

Solid-state-ligand-exchange free high-efficiency colloidal quantum dot solar cells were developed by direct coating of n-type and p-type quantum dot inks.

Highly efficient cathodes for dye-sensitized solar cells (DSSCs) were developed using thin films of graphene nanosheets (GNS), which were fabricated by the electrospray method (e-spray) using aqueous dispersions of chemically driven GNS. The e-sprayed GNS films had the appropriate properties to be an efficient counter electrode (CE) for DSSCs; sufficient electrocatalytic activity for I(-)/I3(-) redox couples and low charge transfer resistance (RCT) at the CE/electrolyte interface as characterize

Low‐temperature solution‐processed high‐efficiency colloidal quantum dot (CQD) photovoltaic devices are developed by improving the interfacial properties of p–n heterojunctions. A unique conjugated polyelectrolyte, WPF‐6‐oxy‐F, is used as an interface modification layer for ZnO/PbS‐CQD heterojunctions. With the insertion of this interlayer, the device performance is dramatically improved. The origins of this improvement are determined and it is found that the multifunctionality of the WPF‐6‐oxy‐