Export 23 results:
Sort by: Author [ Title  (Desc)] Type Year
A B C D E F G H [I] J K L M N O P Q R S T U V W X Y Z   [Show ALL]
Wang, CT, Ma* KJ, Chen KH, Chen LC, Kichambare PD.  2001.  Ion beam sputtered growth and mechanical properties of SiCN films. J. of Mater. Sci. and Engineering. 33:38.
Wei-ChaoChen, Cheng-YingChen, Lin Y-R, Chang J-K, Chen C-H, Chiu Y-P, Wu C-I, Chen K-H, Chen L-C.  2019.  Interface engineering of CdS/CZTSSe heterojunctions for enhancing the Cu2ZnSn(S,Se)4 solar cell efficiency. Materials Today Energy. 13:256-266. AbstractWebsite

Interface engineering of CdS/CZTS(Se) is an important aspect of improving the performance of buffer/absorber heterojunction combination. It has been demonstrated that the crossover phenomenon due to the interface recombination can be drastically eliminated by interface modification. Therefore, in-depth studies across the CdS/CZTS(Se) junction properties, as well as effective optimization processes, are very crucial for achieving high-efficiency CZTSSe solar cells. Here, we present a comprehensive study on the effects of soft-baking (SB) temperature on the junction properties and the corresponding optoelectronic and interface-structural properties. Based on in-depth photoemission studies corroborated with structural and composition analysis, we concluded that interdiffusion and intermixing of CZTSSe and CdS phases occurred on the Cu-poor surface of CZTSSe at elevated SB temperatures, and the interface dipole moments induced by electrostatic potential fluctuation were thus significantly eliminated. In contrast, with low SB temperature, the CdS/CZTSSe heterojunction revealed very sharp interface with very short interdiffusion, forming interface dipole moments and drastically deteriorating device performance. These post thermal treatments also significantly suppress defect energy level of interface measured by admittance spectroscopy from 294 to 109 meV due to CdS/CZTSSe interdiffusion. Meanwhile, the interdiffusion effects on the shift of valence band maximum, conduction band minimum and band offset across the heterojunction of thermally treated CdS/CZTSSe interface are spatially resolved at the atomic scale by measuring the local density of states with cross-sectional scanning tunneling microscopy and spectroscopy. A significant enhancement in the power conversion efficiency from 4.88% to 8.48% is achieved by a facile interface engineering process allowing a sufficient intermixing of CdS/Cd and CZTSSe/Se phases without detrimental recombination centers.

Wu, JS, Chen YF, Dhara S, Wu CT, Chen KH, Chen* LC.  2003.  Interface energy of Au7Si grown in the interfacial layer of truncated hexagonal dipyramidal Au nanoislands on polycrystalline-silicon. Appl. Phys. Lett.. 82:4468-4470.
Mazur, E, Chen KH, Wang J.  1986.  The Interaction of Infrared Radiation with Isolated Molecules: intramolecular nonequilibrium. Int. Conf. on Lasers 6. :359., Orlando
Su, C, Tsai CS, Lin TE, Chen KH, Wang JK, Lin JC.  2000.  Interaction of atomic hydrogen with a Ge(111) surface: LEED and surface Raman studies. Surface Science. 445:139-150.
Cheng*, HC, Hong WK, Tarntair FG, Chen KJ, Lin JB, Chen KH, Chen LC.  2001.  Integration of thin film transistor controlled carbon nanotubes for field-emission devices. Electrochemical and Solid-State Letters. 4 (4):H5-H7.
Pathak, A, Shen J-W, Usman M, Wei L-F, Mendiratta S, Chang Y-S, Sainbileg B, Ngue C-M, Chen R-S, Hayashi M, Luo T-T, Chen F-R, Chen K-H, Tseng T-W, Chen L-C, Lu K-L.  2019.  Integration of a (–Cu–S–)n plane in a metal–organic framework affords high electrical conductivity, 2019. 10(1):1721. AbstractWebsite

Designing highly conducting metal–organic frameworks (MOFs) is currently a subject of great interest for their potential applications in diverse areas encompassing energy storage and generation. Herein, a strategic design in which a metal–sulfur plane is integrated within a MOF to achieve high electrical conductivity, is successfully demonstrated. The MOF {[Cu2(6-Hmna)(6-mn)]·NH4}n (1, 6-Hmna = 6-mercaptonicotinic acid, 6-mn = 6-mercaptonicotinate), consisting of a two dimensional (–Cu–S–)n plane, is synthesized from the reaction of Cu(NO3)2, and 6,6′-dithiodinicotinic acid via the in situ cleavage of an S–S bond under hydrothermal conditions. A single crystal of the MOF is found to have a low activation energy (6 meV), small bandgap (1.34 eV) and a highest electrical conductivity (10.96 S cm−1) among MOFs for single crystal measurements. This approach provides an ideal roadmap for producing highly conductive MOFs with great potential for applications in batteries, thermoelectric, supercapacitors and related areas.

Shit, SC, Shown I, Paul R, Chen K-H, Mondal J, Chen L-C.  2020.  Integrated nano-architectured photocatalysts for photochemical CO2 reduction, 2020. Nanoscale. 12(46):23301-23332.: The Royal Society of Chemistry AbstractWebsite

Recent advances in nanotechnology, especially the development of integrated nanostructured materials, have offered unprecedented opportunities for photocatalytic CO2 reduction. Compared to bulk semiconductor photocatalysts, most of these nanostructured photocatalysts offer at least one advantage in areas such as photogenerated carrier kinetics, light absorption, and active surface area, supporting improved photochemical reaction efficiencies. In this review, we briefly cover the cutting-edge research activities in the area of integrated nanostructured catalysts for photochemical CO2 reduction, including aqueous and gas-phase reactions. Primarily explored are the basic principles of tailor-made nanostructured composite photocatalysts and how nanostructuring influences photochemical performance. Specifically, we summarize the recent developments related to integrated nanostructured materials for photocatalytic CO2 reduction, mainly in the following five categories: carbon-based nano-architectures, metal–organic frameworks, covalent-organic frameworks, conjugated porous polymers, and layered double hydroxide-based inorganic hybrids. Besides the technical aspects of nanostructure-enhanced catalytic performance in photochemical CO2 reduction, some future research trends and promising strategies are addressed.

Hu, MS, Hsu GM, Chen* KH, Yu CJ, Hsu HC, Chen LC, Hwang JH, Hong LS, Chen YF.  2007.  Infrared lasing in InN nanobelts. Appl. Phys. Lett.. 90:123109.
Chang, CK, Hwang JY, Lai WJ, Chen CW, Huang CI, Chen KH, Chen LC.  2010.  Influence of solvent on the dispersion of single-walled carbon nanotubes in polymer matrix and the photovoltaic performance. J. Phys. Chem.. C114:10932-10936.
Z. H. Shen, Hess* P, Huang JP, Lin YC, Chen KH.  2006.  Influence of oxygen on the elastic properties of nanocrystalline diamond films studied by laser-induced surface acoustic waves. Ultrasonics. 44:e1229-e1232.
Rajeev Gandhi, J, Nehru R, Chen S-M, Sankar R, Bayikadi KS, Sureshkumar P, Chen K-H, Chen L-C.  2018.  Influence of GeP precipitates on the thermoelectric properties of P-type GeTe and Ge0.9−xPxSb0.1Te compounds, 2018. CrystEngComm. 20(41):6449-6457.: The Royal Society of Chemistry AbstractWebsite

Germanium telluride (GeTe) is a very well known IV–VI group semiconducting material with the advantageous property of showing metallic conduction, which materializes from its superior carrier concentration (n) (high number of Ge vacancies). A systematic investigation into the thermoelectric properties (TEP) of GeTe was reported by way of carrier concentration (n) engineering. The present investigation focuses on studying the effects of doping (antimony – Sb) and co-doping (phosphorus – P) on the TEP of GeTe. In order to understand the system, we have prepared p-type GeTe and Ge0.9−xPxSb0.1Te (x = 0, 0.01, 0.03, or 0.05) samples via a non-equilibrium solid state melt quenching (MQ) process, followed by hot press consolidation. Temperature dependent synchrotron X-ray diffraction studies reveal a phase transition from rhombohedral to simple cubic in the Ge0.9−xPxSb0.1Te system at 573 K, which is clearly reflected in the TEP. Further high resolution transmission electron microscopy (HRTEM) studies reveal the pseudo-cubic nature of the sample. However, powder X-ray diffraction (PXRD) and field emission scanning electron microscopy (FESEM) images and energy dispersive X-ray spectroscopy (EDX) studies confirm the presence of germanium phosphide (GeP) in all P-doped samples. The presence of a secondary phase and point defects (Sb & P) enhanced the additional scattering effects in the system, which influenced the Seebeck coefficient and thermal conductivity of GeTe. A significant enhancement in the Seebeck coefficient (S) to ∼225 μV K−1 and a drastic reduction in thermal conductivity (κ) to ∼1.2 W mK−1 effectively enhanced the figure-of-merit (ZT) to ∼1.72 at 773 K for Ge0.87P0.03Sb0.1Te, which is a ∼3 fold increase for GeTe. Finally, P co-doped Ge0.9Sb0.1Te demonstrates an enhancement in ZT, making it a good candidate material for power generation applications.

Fang, WC, Huang* JH, Chen LC, Chen KH, Su OYH.  2007.  Influence of catalyst oxidation on the growth of nitrogen-containing carbonnanotubes for energy generation and storage applications. Diamond Relat. Mater.. 16:1140-1143.
Chen, IN, Chong CW, Lyu LM, Wong DP, Chien WL, Anbu A, Chen YF, Chen LC, Chen KH.  2016.  Improving the thermoelectric performance of metastable rock-salt GeTe-rich Ge-Sb-Te thin films through tuning of grain orientation and vacancies. Physica Status Solidi A . :1-8.
Basilio, AM, Hsu YK, Tu WH, Hsu GM, Chen LC, Chen* KH.  2010.  Improving the photoelectrochemical and H2gas generation property of c-plane GaN thin film through crystallographic etching of the film. J. Mater. Chem.. 20:8118-8125.
K. J. Chen, Hong WK, Lin CP, Chen KH, Chen* LC, Cheng HC.  2002.  Improvement of field emission characteristics of carbon nanotubes by eximer laser treatment. Jpn. J. Appl. Phys.. 41:6132-6136.
Ebrahimi, M, Samadi M, Yousefzadeh S, Soltani M, Rahimi A, Chou T-chin, Chen L-C, Chen K-H, Moshfegh AZ.  2017.  Improved Solar-Driven Photocatalytic Activity of Hybrid Graphene Quantum Dots/ZnO Nanowires: A Direct Z-Scheme Mechanism, 2017. ACS Sustainable Chemistry & EngineeringACS Sustainable Chemistry & Engineering. 5(1):367-375.: American Chemical Society AbstractWebsite
Huang, YF, Chattopadhyay S, Jen YJ, Peng CY, Liu TA, Hsu YK, Pan CL, Lo HC, Hsu CH, Chang YH, Lee CS, Chen KH, Chen LC.  2007.  Improved broadband, and quasi-omnidirectional anti-reflection properties with biomimetic silicon nanostructures. Nature Nanotechnology. 2:770-774.
Kuo, CT, Lu TR, Chen LC, Chen KH.  2000.  Implication from using two different bio-molecular materials to synthesize crystalline carbon nitride films. J. Vac. Sci. Tech. B. 18:1207.
Quadir, S, Qorbani M, Lai Y-R, Sabbah A, Thong H–T, Hayashi M, Chen C–Y, Chen K–H, Chen L–C.  2021.  Impact of Cation Substitution in (AgxCu1−x)2ZnSnSe4 Absorber-Based Solar Cells toward 10% Efficiency: Experimental and Theoretical Analyses, 2021. Solar RRLSolar RRL. n/a(n/a):2100441.: John Wiley & Sons, Ltd AbstractWebsite

Solar cells based on kesterite Cu2ZnSnSe4 (CZTSe) compounds with earth-abundant elements are highly desirable for the low-cost and high-efficiency production of renewable energy. However, the occurrence of intrinsic defects substantially impairs the photovoltaic properties of CZTSe. Herein, a cation substitution method to control and passivate the defect states in bandgap of kesterite CZTSe by incorporating Ag ions is introduced. Intensity-dependent low-temperature photoluminescence measurements show that Ag incorporation can reduce the density and depth of intrinsic defects in CZTSe. The results reveal that 10% Ag-alloyed CZTSe provides the shallowest defect states and less nonradiative recombination. It is also confirmed by first-principles calculations that Ag incorporation enables the formation and suppresses the beneficial and detrimental defects, respectively. Based on the theoretical results, the observed subband photoluminescence peaks can be assigned to the intrinsic point and cluster defects. The best power conversion efficiency of 10.2% is achieved for the 10% Ag-alloyed CZTSe cell, along with an enhanced open-circuit voltage. These results open up a new avenue for further improving the performances of CZTSe-based device via defect engineering.

Hwang, JS, Lin YH, Hwang JY, Chang R, Chattopadhyay S, Chen CJ, Chen P, Chiang HP, Tsai TR, Chen LC, Chen KH.  2013.  Imaging layer number and stacking order through formulating Raman fingerprints obtained from hexagonal single crystals of few layer graphene. Nanotechnology. 24:015702.