學術出版;;Publications

Permanent URI for this communityhdl:11536/1

收集所有交通大學研究人員與學生個人或團體所發表之各項學術著作，涵蓋期刊論文、教師專書、學位論文等項。;;Collections of Publications of NCTU Researchers and Students Like Journal Papers and Thesis.

Browse

🏛️國立陽明交通大學機構典藏

Search Results

Now showing 1 - 10 of 142

Synthesis and luminescent properties of polymer-silica multilayer-encapsulated perovskite quantum dots for optoelectronics
(1970-01-01)
Liu, Shuang-De
;
Chen, Teng-Ming
;
應用化學系
;
Department of Applied Chemistry
Hydrophobic all-inorganic perovskite quantum dots (IPQDs) CsPbX3 (X = Cl, Br, and I) were synthesized using conventional solution methods. IPQDs are potential materials for lasers, solar cells, and displays because of their narrow full width at half-maximum, optically tunable wavelength, and great photoluminescence quantum yield. Their shortcomings are structurally unstable and moisture sensitive. To overcome the poor stability, we have developed a chemical modification to form GQD + PMAO@SiO2 that enhances their photoluminescence quantum yield (from 60 to similar to 90%), thermal stability (from 60 to similar to 90 degrees C), and photochemical stability. The combination of the green-emitting GQD + PMAO@SiO2 and red-emitting RQD + PMAO with a 450 nm blue InGaN-based LED chip was used to fabricate a white light emitting diode with the correlated color temperature (CCT) value of 6,943 K and Commission Internationale del'Eclairage of (0.312, 0.290).
Synthesis, photoluminescence, and electroluminescence characterization of double tetraphenylethene-tethered BODIPY luminogens
(1970-01-01)
Yang, Chiun-Jen
;
Lee, Jian Haur
;
Chen, Chin-Ti
;
應用化學系
;
Department of Applied Chemistry
Three double tetraphenylethene (TPE)-tethered 4-difluoro-4-bora-3a,4a-diaza-s-indance (BODIPY) fluorophores, 35TPEBODP, 88TPEBODP, and 26TPEBODP, have been synthesized and characterized. The green 35TPEBODP with deep red fluorescence shows serious thermal decomposition in the purification process of sublimation, which prohibits its test for an organic light-emitting diode (OLED) fabricated by the vacuum-thermal evaporation process. The tethered TPE is attached to BODIPY at three different positions, resulting in different photoluminescence (emission wavelength and quantum yield) and electroluminescence (EL). Different from TPE-tethered BODIPY fluorophores reported in literature, none of the BODIPY fluorophores studied here exhibits aggregation-induced emission (AIE), aggregation-induced enhanced emission (AIEE), or twisted intramolecular charge transfer (TICT) characteristics. Although solution (10(-5) M THF) photoluminescence quantum yields (phi s) are relatively high at 78%, 68%, and 86% for 35TPEBODP, 88TPEBODP, and 26TPEBODP, respectively, which are all higher than 41% of PhBODP (a non-TPE-tethered BODIPY), the phi is significantly decreased to 1-6% in 5 wt% dopant polystyrene thin film or as a solid powder, except for 13% of 26TPEBODP. Therefore, due to the low phi of dopant thin film or solid powder, either dopant or nondopant OLEDs exhibit inferior external quantum efficiency (EQE) and intensity of EL. The best OLED in this study is the 26TPEBODP device, and its EQE reaches 1.3%, and the highest EL intensity is approximately 1,600 cd/m(2).
Abnormal PL spectrum in InGaN MQW surface emitting cavity
(2008-01-01)
Chu, J. T.
;
Cheng, Y. -J.
;
Kuo, H. C.
;
Lu, T. C.
;
Wang, S. C.
We report the observation of an abnormal photoluminescent (PL) spectrum from a HeCd laser pumped InGaN multiple quantum well (MQW) vertical cavity. The device is fabricated using standard MOCVD deposition on a (0001)-oriented sapphire substrate. The layer structures are: 10nm nucleation layer, a 4um bulk GaN layer, InGaN MQWs, and a final 200nm GaN cap layer. The InGaN MQWs consist of 10 pairs of 5 nm GaN barrier and 3 run In0.1Ga0.9N well. The peak emission of the as-grown MQWs sample was similar to 420nm. A dielectric distributed Bragg reflectors (DBR) were then coated on the top layer, followed by a laser lift off from sapphire substrate, and subsequently another DBR coated on the bulk GaN bottom surface. The cavity has a quality factor of similar to 520 from 400-490nm. The device was pumped by a focused CW HeCd laser from the bulk GaN side. When the laser is focused onto the InGaN MQWs, a photoluminescent spectrum centered at the designed MOW wavelength was observed as expected. However, when the focused position was moved toward the bulk GaN region, an additional abnormal PL peak around 460nm was observed. This is far outside the designed MQW wavelength.
Effects of substrate temperature on properties of Alq3 amorphous layers prepared by vacuum deposition
(2006-01-01)
Chiu, K. C.
;
Jian, Z. A.
;
Luo, Y. Z.
;
Chung, J. M.
;
Tang, S. J.
In this report, various organic Alq3 amorphous layers are prepared by vacuum deposition at different substrate temperatures T-sub (from 30 to 180 degrees C). The surface morphology, structural information, electrical and optical properties of these as-deposited layers are investigated by atomic force microscopy, X-ray diffraction, J-E curves, and photoluminescence studies, respectively. Furthermore, a temperature dependence of dark electrical conductivity sigma(T) deduced from J-E curves of these organic amorphous layers is presented. Finally, effects from T-sub on the physical properties of these organic Alq3 amorphous layers are discussed and a model based on a thermal interconversion between Alq3 isomers is proposed to explain these experimental results.
Single-exciton energy shell structure in InAs/GaAs quantum dots
(2008-12-01)
Awirothananon, S.
;
Raymond, S.
;
Studenikin, S.
;
Vachon, M.
;
Render, W.
The energy shell structure of a single exciton confined in a self-assembled quantum dot (QD), including excited states, is studied in a regime where the direct Coulomb attraction energy is comparable to the kinetic energy of the carriers. This is achieved via magnetophotoluminescence excitation spectroscopy experiments, where a magnetic field applied perpendicular to the plane of the QD is used to reveal the angular-momentum content of energy shells. The absorption spectrum of the QDs is modeled, and comparison with experiment allows us to relate the observed transitions to interband QD bound-state transitions. The blueshift of the absorption peaks compared to the emission peaks is then interpreted in terms of many-body interactions, and we show that for a highly symmetric situation, the observed energy difference gives a direct measurement of the extra exchange energy gained upon addition of an extra exciton in the QD.
The Effect of Tensile Strain on Optical Anisotropy and Exciton of m-Plane ZnO
(2015-04-01)
Wang, H. H.
;
Tian, J. S.
;
Chen, C. Y.
;
Huang, H. H.
;
Yeh, Y. C.
The near band edge emission of the tensile-strained m-plane ZnO film grown on (112)LaAlO3 substrates shows abnormal low polarization degree (rho = 0.1). The temperature dependency of polarization degree clarifies the origins of different emission peaks. In tensile-strained m-plane ZnO, the [0001] polarized state is upper shifted and is overlapping with the [11 (2) over bar0] polarized state. This phenomenon causes the abnormal low polarization degree and reveals the effect of strain on the emission anisotropy of m-plane ZnO.
Recombination lifetimes in InN films studied by time-resolved excitation-correlation spectroscopy
(2009-11-01)
Liu, Horng-Chang
;
Hsu, Chia-He
;
Chou, Wu-Ching
;
Chen, Wei-Kuo
;
Chang, Wen-Hao
Recombination dynamics in degenerate InN were investigated by means of time-resolved excitation-correlation spectroscopy. The photoluminescence decay times are determined beyond the spectral response and temporal resolution limits of conventional photon-counting detectors. Spectral and temperature dependence of decay times reveal the effects of hole localizations on the recombination mechanisms. At low temperatures, the radiative lifetime tau(r) is insensitive to temperature and significantly longer than that predicted for the radiative band-to-band recombination, indicative of a transition dominated by the free-to-bound recombination without k conservation. Above a certain temperature determined by the electron concentration, we find tau(r)similar to T(3/2), as expected for the band-to-band transition when the k-selection rule holds. We determine a lower limit for the bimolecular recombination coefficient B in InN at 300 K as 5.6x10(-11) cm(3)/s.
Improvement of perovskite photoluminescence characteristics by using a lithography-free metasurface
(2018-01-01)
Chen, Wenjun
;
Sha, Jun
;
Yan, Kanghong
;
Luo, Ji
;
Xu, Ruijia
Organic-inorganic metal halid perovskite is an emerging field of promising semiconductive material in optoelectronic devices applications. It has been a research topic of interest for scientists. To date, photoluminescence (PL) efficiency of perovskite is low and does not have any literature to report the solution. Here, we proposed and demonstrated an effective approach for the improvement of perovskite PL characteristics. The PL intensity and spectra bandwidth could be enhanced significantly by using Al-disk metasurface formed on perovskite surface. Such strategy can be exploited to enhance perovskite PL characteristics for developing high efficient light emitting diodes, solar cells, and photodetectors, etc.
Time-resolved photoluminescence of isoelectronic traps in ZnSe1-xTex semiconductor alloys
(2008-12-15)
Lin, Y. C.
;
Chou, W. C.
;
Fan, W. C.
;
Ku, J. T.
;
Ke, F. K.
Kohlrausch's stretched exponential law correlates well with the photoluminescence (PL) decay profiles of ZnSe1-xTex. As the Te concentration increases, the stretching exponent beta initially declines and then monotonically increases. This result can be understood using the hopping-transport and energy transfer model. The increase in the number of isoelectronic Te localized traps can reduce the PL decay rate and increase the linewidth, whereas the hybridization of the Te localized states with the valence-band edge states causes a reduction in both the lifetime and linewidth.
Photoluminescence-Driven Broadband Transmitting Directional Optical Nanoantennas
(2018-09-01)
See, Kel-Meng
;
Lin, Fan-Cheng
;
Chen, Tzu-Yu
;
Huang, You-Xin
;
Huang, Chen-Hsien
Optical nanoantennas mediate near and far optical fields. Operating a directional nanoantenna in transmitting mode is challenging because the antenna needs to be driven by a nanosized optical frequency generator, which must work at the antenna's resonance frequency and be precisely attached to the antenna's feed with correct polarization. Quantum emitters have been used as optical nanogenerators, but their precise positioning relative to the nanoantenna is technically challenging, setting up a barrier to the practical implementation. One unique source to drive nanoantenna is the photoluminescence from the material of the nanoantenna because the high operational frequency of the antenna reaches the regime for the electronic transitions in matter. Here, we exploit plasmon-modulated photoluminescence (PMPL) as an effective optical source to drive directional nanoantennas. We experimentally realize two technically challenging theoretical proposals, namely, an optical nanospectrometer based on Yagi-Uda nanoantennas and tunable broadband directional emission from log-periodic nanoantennas. Using photoluminescence from the nanoantenna as an optical source promotes practical implementation of transmitting optical nanoantennas.

學術出版;;Publications

Browse

Filters

Settings

Sort By

Results per page

🏛️國立陽明交通大學機構典藏

Search Results