Kuo-Chuan Ho

Bio: Kuo-Chuan Ho is an academic researcher from National Taiwan University. The author has contributed to research in topics: Dye-sensitized solar cell & Electrochromism. The author has an hindex of 74, co-authored 506 publications receiving 21485 citations. Previous affiliations of Kuo-Chuan Ho include Indian Institute of Technology Roorkee & University of Rochester.

Highly conductive PEDOT:PSS electrode by simple film treatment with methanol for ITO-free polymer solar cells

Abstract: We proposed a simple yet robust film treatment method with methanol having only one hydroxyl group to enhance the conductivity of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) by four orders of magnitude. Different methods of film treatment: immersing PEDOT:PSS film in the methanol solution; dropping methanol on the film; and a combination of these are employed and the results are compared. The conductivity of PEDOT:PSS films was enhanced from 0.3 S cm−1 to 1362 S cm−1 after film treatment with methanol. Other alcohols like ethanol and propanol were also used to treat the PEDOT:PSS film and showed inferior conductivity enhancement compared to methanol. The conductivity enhancement was greatly affected by the hydrophilicity and dielectric constant of the alcohols used. The mechanism of conductivity enhancement was investigated through various characterization techniques including FTIR, XPS and AFM. Removal of the insulator PSS from the film, and morphology and conformational changes are the mechanisms for the conductivity enhancement. The treated films also showed high transmittance and low sheet resistance desirable for a standalone electrode. ITO-free polymer solar cells were fabricated using PEDOT:PSS electrodes treated with methanol and showed almost equal performance to ITO electrodes.

2,3-Disubstituted Thiophene-Based Organic Dyes for Solar Cells

Abstract: New organic dyes that contain variable lengths of conjugation, featuring oligothiophene and arylamines at the 2- and 3-position, have been synthesized. These compounds are characterized by photophysical, electrochemical, and theoretical computational methods. Nanocrystalline TiO2-based dye-sensitized solar cells were fabricated using these molecules as light-harvesting sensitizers. The overall efficiencies of the sensitized cells range from 4.11 to 6.15%, compared to a cis-di(thiocyanato)-bis(2,2′-bipyridyl)-4,4′-dicarboxylate ruthenium(II)-sensitized device (7.86%) fabricated and measured under similar conditions. The devices made from these compounds have higher open-circuit voltage (VOC) compared to oligothiophene congeners with arylamines at the 2-position only. The hydrophobic segment at the 3-position appears to help retarding the charge transfer from the conduction band of TiO2 to the electrolyte, I3−. Supplementary studies of the transient photovoltage and electrochemical impedance are in support ...

A Ruthenium Complex with Superhigh Light‐Harvesting Capacity for Dye‐Sensitized Solar Cells

Abstract: A dye-sensitized solar cell (DSSC) using Ru complexes as a photosensitizer was first reported by O Regan and Gr\"tzel in 1991. The low-cost, easy preparation make DSSC one of the most promising photovoltaic cells for conversion of sunlight to electricity. Numerous sensitizers have been prepared, and their performance has been tested. A conversion efficiency of up to 11% was achieved by using cis-di(thiocyanato)bis(2,2’-bipyridyl-4,4’-dicarboxylate)ruthenium(II) (N3) as a photosensitizer. However, the conversion efficiency of DSSCs is still lower than that of the silicon-based photovoltaic cells. To obtain a high conversion efficiency, optimization of the short-circuit photocurrent (Isc) and open-circuit potential (Voc) of the cell is essential. The value of Voc depends on the edge of conduction band in TiO2 and the redox potential of I / I3 , otherwise Isc is related to the interaction between TiO2 and the sensitizer as well as the absorption coefficient of the sensitizer. The conduction band of TiO2 was known to have a Nernstian dependence on pH. Thus, the molecular engineering of the ruthenium complexes for achieving the highest efficiency was attempted to increase the molar absorption coefficient and reduce the number of protons on the complexes. 4,4’-Dicarboxylic acid-2,2’-bipyridine (dcbpy) has been considered as the best anchoring ligand in Ru sensitizers. Finding new metal-complex sensitizers with higher conversion efficiency was achieved by modifying one of the anchoring ligands. Replacement of one of the dcbpy anchoring ligands with a highly conjugated ancillary ligand represents a molecular engineering approach for increasing the absorption coefficient and therefore the photocurrent density of the sensitizers as reported by Gr\"tzel and coworkers. Herein, we report a new ruthenium photosensitizer CYC-B1 in which one of the dcbpy ligands in N3 was replaced with abtpy, a bipyridine ligand substituted with alkyl bithiophene groups. CYC-B1 has the highest absorption coefficient among the Ru-based photosensitizers used in DSSCs, and its power-conversion efficiency is 10% higher than that ofN3 under the same cell fabrication and measuring procedures carried out in our laboratory. CYC-B1 was prepared in a typical one-pot synthesis, and its structure (Scheme 1) was identified from NMR

CoS acicular nanorod arrays for the counter electrode of an efficient dye-sensitized solar cell.

Abstract: One-dimensional cobalt sulfide (CoS) acicular nanorod arrays (ANRAs) were obtained on a fluorine-doped tin oxide (FTO) substrate by a two-step approach. First, Co3O4 ANRAs were synthesized, and then they were converted to CoS ANRAs for various periods. The compositions of the films obtained after various conversion periods were verified by X-ray diffraction, UV–visible spectrophotometry, and X-ray photoelectron spectroscopy; their morphologies were examined at different periods by scanning electron microscopic and transmission electron microscopic images. Electrocatalytic abilities of the films toward I–/I3– were verified through cyclic voltammetry (CV) and Tafel polarization curves. Long-term stability of the films in I–/I3– electrolyte was studied by CV. The FTO substrates with CoS ANRAs were used as the counter electrodes for dye-sensitized solar cells; a maximum power conversion efficiency of 7.67% was achieved for a cell with CoS ANRAs, under 100 mW/cm2, which is nearly the same as that of a cell wit...

Dye-Sensitized Solar Cells

Abstract: Dye-sensitized solar cells (DSCs) offer the possibilities to design solar cells with a large flexibility in shape, color, and transparency. DSC research groups have been established around the worl ...

Semiconductor-based Photocatalytic Hydrogen Generation

Abstract: 2.3. Evaluation of Photocatalytic Water Splitting 6507 2.3.1. Photocatalytic Activity 6507 2.3.2. Photocatalytic Stability 6507 3. UV-Active Photocatalysts for Water Splitting 6507 3.1. d0 Metal Oxide Photocatalyts 6507 3.1.1. Ti-, Zr-Based Oxides 6507 3.1.2. Nb-, Ta-Based Oxides 6514 3.1.3. W-, Mo-Based Oxides 6517 3.1.4. Other d0 Metal Oxides 6518 3.2. d10 Metal Oxide Photocatalyts 6518 3.3. f0 Metal Oxide Photocatalysts 6518 3.4. Nonoxide Photocatalysts 6518 4. Approaches to Modifying the Electronic Band Structure for Visible-Light Harvesting 6519

Aggregation-Induced Emission: Together We Shine, United We Soar!

Abstract: Ju Mei,†,‡,∥ Nelson L. C. Leung,†,‡,∥ Ryan T. K. Kwok,†,‡ Jacky W. Y. Lam,†,‡ and Ben Zhong Tang*,†,‡,§ †HKUST-Shenzhen Research Institute, Hi-Tech Park, Nanshan, Shenzhen 518057, China ‡Department of Chemistry, HKUST Jockey Club Institute for Advanced Study, Institute of Molecular Functional Materials, Division of Biomedical Engineering, State Key Laboratory of Molecular Neuroscience, Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China Guangdong Innovative Research Team, SCUT-HKUST Joint Research Laboratory, State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Guangzhou 510640, China

Pseudocapacitive oxide materials for high-rate electrochemical energy storage

Abstract: Electrochemical energy storage technology is based on devices capable of exhibiting high energy density (batteries) or high power density (electrochemical capacitors). There is a growing need, for current and near-future applications, where both high energy and high power densities are required in the same material. Pseudocapacitance, a faradaic process involving surface or near surface redox reactions, offers a means of achieving high energy density at high charge–discharge rates. Here, we focus on the pseudocapacitive properties of transition metal oxides. First, we introduce pseudocapacitance and describe its electrochemical features. Then, we review the most relevant pseudocapacitive materials in aqueous and non-aqueous electrolytes. The major challenges for pseudocapacitive materials along with a future outlook are detailed at the end.