Chin-Jung Lin

Transparent electrodes of ordered opened-end TiO2-nanotube arrays for highly efficient dye-sensitized solar cells

We introduce a version of a dye-sensitized solar cell (DSSC), in which the transparent electrode comprises an opened-end TiO2-nanotube (TiNT) film oriented perpendicular to the fluorine-doped tin oxide (FTO) conductive glass. This electrode is fabricated using a facile process involving flaking the anodic TiNT film off the Ti-metal substrate to open its closed bottom and strongly adhering it onto FTO glass by a nanocrystalline TiO2 (NP-TiO2) thin underlayer. Apart from the enhanced light-harvesting and electron-collecting efficiencies, the use of opened-end TiNT film allows the redox electrolyte (iodide, I− and triiodide, I3−) easy access to the NP-TiO2 underlayer. As compared to the closed-end TiNT-based DSSC, the opened-end TiNT-based device exhibited an increase in one-sun efficiency from 5.3% to 9.1%, corresponding to 70% enhancement.

Fabrication of open-ended high aspect-ratio anodic TiO2 nanotube films for photocatalytic and photoelectrocatalytic applications.

A facile process is introduced to flake high aspect-ratio anodic TiO(2) nanotube (TiNT) arrays off Ti substrates and then chemically remove the bottom caps to obtain open-ended TiNT films that exhibit high activity to photocatalytic degradation of methylene blue and efficient hydrogen production from photoelectrocatalytic water splitting.

Surface modification of highly ordered TiO2 nanotube arrays for efficient photoelectrocatalytic water splitting

An efficient visible-light-sensitive heterostructure photoanode of CdS nanoparticles/ZnO shell/TiO2 nanotube (CdS/ZnO–TiNT) arrays were investigated for solar water splitting. Highly ordered arrays of TiNT were grown vertically on Ti foil by electrochemical anodization. Both aqueous solution routes were used in turn to coat a thin recombination barrier of ZnO shell and narrow band gap CdS nanoparticles to the surface of the TiNT arrays. As a result of strong absorption within solar spectrum and effective suppression of electron-hole pair recombination in CdS/ZnO–TiNT arrays, a significant improvement in solar-to-hydrogen conversion efficiency from 0.39% to 1.30% was obtained.

Rough conical-shaped TiO2-nanotube arrays for flexible backilluminated dye-sensitized solar cells

Conical-shaped anodic TiO2-nanotube (TiNT) arrays with length of a few tens of micrometer and rough tube walls were fabricated for use in flexible backilluminated dye-sensitized solar cells (DSSCs) which exhibited conversion efficiency of 4.3% under AM1.5 back side illumination. As compared to TiO2 nanoparticles/Ti-based DSSC, TiNT/Ti-based DSSC showed enhanced light-harvesting efficiency, rapid electron-transport rate, prolonged electron lifetime, and reduced dark current, leading to an increase in efficiency by ∼30%.

Effect of anodic TiO2 powder as additive on electron transport properties in nanocrystalline TiO2 dye-sensitized solar cells

Highly crystalline anodic TiO2 (AO-TiO2) powder was obtained by grinding of annealed TiO2 nanotube arrays grown using anodization of Ti foil. The influence of AO-TiO2 as additive in nanocrystalline TiO2 film on electron transport properties affecting the performance of these dye-sensitized solar cell was investigated using electrochemical impedance spectroscopy and the open-circuit voltage decay technique under AM 1.5 illumination. As a result of the enhanced charge-collection and light harvesting efficiencies, an increase of above 20% in photocurrent density was observed after the addition of AO-TiO2.

Organic bistable memory based on Au nanoparticle/ZnO nanorods composite embedded in poly (vinylpyrrolidone) layer

Organic non-volatile memory devices were fabricated by embedding Au nanoparticle (NP)/ZnO nanorods (NRs) composite in an insulating poly (vinylpyrrolidone) as the active layer. The complete active materials were synthesized with an entire aqua solution process. Transmission electron microscopy images revealed that the Au NP/ZnO NRs composite exhibits an aster-like structure where Au NP is at the center while ZnO NRs are surrounding. Current-voltage (I-V) measurements of such device demonstrated electrical bistability with excellent on/off ratio of 4 × 103 under 1 V reading voltage. We attributed the high on/off ratio of the memory device to the large surface area of the Au NP/ZnO NRs composite where large amount of charges can be stored. In addition, the surrounding ZnO NRs act as spacers, which can effectively prevent the center gold nanoparticles from aggregation. Consequently, a low current leakage can be expected. Our study paved a way of employing a nanocomposite as a material for high performance or...

Type-II heterojunction organic/inorganic hybrid non-volatile memory based on FeS2 nanocrystals embedded in poly(3-hexylthiophene)

Electrical bistable behaviour was demonstrated in memory devices based on n-type FeS2 nanocrystals (NCs) embedded in a p-type poly(3-hexylthiophene) (P3HT) matrix. An organic/inorganic hybrid non-volatile memory device with a type-II band alignment, fabricated by a spin-coating process, exhibited electrical bistable characteristics. The bistable behaviour of carrier transport can be well described through the space-charge-limited current model. The small amount of FeS2 NCs in this device serve as an excellent charge trapping medium arising from the type-II band alignment between FeS2 and P3HT. Our study suggests a new way to integrate non-volatile memory with other devices such as transistor or photovoltaic since the presented FeS2/P3HT offers a type-II band alignment.