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 127

Accumulated plasmonic effects of gold nanoparticle-decorated PEGylated graphene oxides in organic light-emitting diodes
(2020-09-01)
Chuang, Ming-Kai
;
Lin, Chun-Hao
;
Chen, Fang-Chung
;
交大名義發表
;
光電工程學系
Amphiphilic Au nanoparticle-decorated PEGylated graphene oxides (Au@PEG-GO) are used to construct multiple plasmonic nanostructures for enhancing the performance of organic light-emitting diodes (OLEDs). Because of the long side-chains of the Au@PEG-GO nanocomposites, the nanoparticles can be well dispersed both in organic and aqueous solvents, allowing them to be incorporated readily into the buffer layers, such as poly(3,4-ethylenedioxythiophene): polystyrenesulfonate (PEDOT:PSS) and the organic photoactive layers within OLEDs during the soultion processes. Herein, the Au@PEG-GO nanocomposites are blended into either the PEDOT:PSS or the emissive layer of OLEDs to trigger surface plasmonic effects, thereby improving the device efficiencies. The current efficiencies are improved by ca. 20% for both cases. More importantly, the simultaneous addition of the Au@PEG-GO nanocomposites into both layers leads to even pronounced plasmonic effects. Under the optimized condition, the current efficiency is enhanced by up to 38%, suggesting the plasmonic fields from both layers attributed to the device enhancement. We anticipate that the accumulated plasmonic effects originating from the multiple plasmonic nanostructures will open up new avenues for improving the performance of various solution-processed optoelectronic devices involving organic dyes.
Plasmonic effects of copper nanoparticles in polymer photovoltaic devices for outdoor and indoor applications
(2020-06-22)
Huang, Chien-Lun
;
Kumar, Gautham
;
Sharma, Ganesh D.
;
Chen, Fang-Chung
;
交大名義發表
The use of metal nanoparticles (NPs) that can trigger localized surface plasmon resonance (LSPR) is an effective method for improving the performance of organic photovoltaics (OPVs). Currently, most plasmonic NPs are based on noble metals, including gold and silver; their high cost limits their commercial applications in the cost-effective OPVs. Herein, copper (Cu) NPs, which are more abundant and cheaper, are adopted to fabricate OPVs. To avoid oxidation of Cu NPs, they are positioned at the cathode interface, so that their fabrication could be implemented in an inert environment. The resulting OPVs exhibited improved power conversion efficiencies (PCEs) under illumination at 1 sun, and the device enhancement could be attributed to the LSPR effects of Cu NPs. Further, their potential to enhance the performance of OPVs under indoor lighting conditions is evaluated. The enhancement factor of PCEs was higher, while the light source had a lower color temperature. It could be due to the fact that the main plasmonic band of the Cu NPs is localized in the red spectral range. The results reveal the consideration of matching between the LSPR spectral range and the emission spectra of the artificial light sources is very critical for indoor applications.
Toward High-Performance Polymer Photovoltaic Devices for Low-Power Indoor Applications
(2017-12-01)
Yang, Shun-Shing
;
Hsieh, Zong-Chun
;
Keshtov, Muchamed L.
;
Sharma, Ganesh D.
;
Chen, Fang-Chung
This article describes the performance of organic photovoltaic (OPV) devices, incorporating three different polymer/fullerene derivative blends, under low-level lighting conditions. The devices exhibit much higher power conversion efficiencies (PCEs) under indoor lighting conditions than they do under sunlight. The best-performing device is capable of delivering a power output of 22.57Wcm(-2), corresponding to a PCE of 13.76%, under illumination with indoor lighting conditions at 500 lux. Increasing the open-circuit voltage (V-oc) of the OPV devices is the most critical factor for achieving high device performance for low-power indoor applications. Therefore, the device power output will be maximized if we could obtain a larger energy difference between the highest occupied molecular orbital of the polymer donor and the lowest unoccupied molecular orbital of the electron acceptor, thereby ensuring a high value of V-oc.
Bandgap Engineering Enhances the Performance of Mixed-Cation Perovskite Materials for Indoor Photovoltaic Applications
(2019-10-01)
Wu, Ming-Ju
;
Kuo, Chien-Chen
;
Jhuang, Lu-Syuan
;
Chen, Po-Han
;
Lai, Yi-Fong
Indoor photovoltaics (IPVs) are attracting renewed interest because they can provide sustainable energy through the recycling of photon energy from household lighting facilities. Herein, the Shockley-Queisser model is used to calculate the upper limits of the power conversion efficiencies (PCEs) of perovskite solar cells (PeSCs) for two types of artificial light sources: fluorescent tubes (FTs) and white light-emitting diodes (WLEDs). An unusual zone is found in which the dependence of the PCEs on the bandgap (E-g) under illumination from the indoor lighting sources follows trends different from that under solar irradiation. In other words, IPVs exhibiting high performance under solar irradiation may not perform well under indoor lighting conditions. Furthermore, the ideal bandgap energy for harvesting photonic power from these indoor lighting sources is approximate to 1.9 eV-a value higher than that of common perovskite materials (e.g., for CH3NH3PbI3). Accordingly, Br- ions are added into the perovskite films to increase their values of E-g. A resulting PeSC featuring a wider bandgap exhibits PCEs of 25.94% and 25.12% under illumination from an FT and a WLED, respectively. Additionally, large-area (4 cm(2)) devices are prepared for which the PCE reaches approximate to 18% under indoor lighting conditions.
Differential Space-Limited Crystallization of Mixed-Cation Lead Iodide Single-Crystal Micro-Plates Enhances the Performance of Perovskite Solar Cells
(2019-10-01)
Sung, Hsin-Hung
;
Kuo, Chien-Chen
;
Chiang, Hung-Sheng
;
Yue, Hong-Lin
;
Chen, Fang-Chung
The synthesis of certain asymmetric perovskite single crystals (SCs)-including CH3NH3PbI3, which is used most commonly-for application in high-performance perovskite solar cells (PeSCs), remains very challenging. Herein, a promising but general method, differential space-limited crystallization (DSLC), is described for synthesizing high-quality perovskite single-crystal micro-plates. The thickness of the perovskite SCs is controlled by the difference between the thicknesses of two sets of polytetrafluoroethylene (PTFE) spacers. Because the DSLC method does not require very thin spacers, it simplifies the procedure of crystal growth. More importantly, the hydrophobicity of the PTFE spacers weakens the attraction between the surfaces of the confined space and the precursor complexes, thereby increasing the rate of diffusion of the precursor ions. Accordingly, the critical nucleation step is not limited by the low rate of diffusion of the ions. This approach is used to prepare mixed-cation lead iodide single-crystalline micro-plates for solar cell applications. The device performance of single-crystal PeSCs improves after introducing formamidinium ions. The stability of the single-crystal devices also improves relative to that of conventional thin-film counterparts. It is anticipated that this DSLC method can also be used to synthesize different types of asymmetrical perovskite SCs for other optoelectronic applications.
Flexible Organometal-Halide Perovskite Lasers for Speckle Reduction in Imaging Projection
(2019-05-01)
Wang, Yu-Chi
;
Li, Heng
;
Hong, Yu-Heng
;
Hong, Kuo-Bin
;
Chen, Fang-Chung
Disorder is emerging as a strategy for fabricating random laser sources with very promising materials, such as perovskites, for which standard laser cavities are not effective or too expensive. We need, however, different fabrication protocols and technologies for reducing the laser threshold and controlling its emission. Here, we demonstrate an effectively solvent-engineered method for high-quality perovskite thin films on a flexible polyimide substrate. The fractal perovskite thin films exhibit excellent optical properties at room temperature and easily achieve lasing action without any laser cavity above room temperature with a low pumping threshold. The lasing action is also observed in curved perovskite thin films on flexible substrates. The lasing threshold can be further reduced by increasing the local curvature, which modifies the scattering strengths of the bent thin film. We also show that the curved perovskite lasers are extremely robust with respect to repeated deformations. Because of the low spatial coherence, these curved random laser devices are efficient and durable speckle-free light sources for applications in spectroscopy, bioimaging, and illumination.
Bidentate chelating ligands as effective passivating materials for perovskite light-emitting diodes
(2019-04-21)
Hsiao, Ming-Chuan
;
Chien, Ping-Cheng
;
Jhuang, Lu-Syuan
;
Chen, Fang-Chung
;
交大名義發表
Herein, four pyridine-based chelating ligands, including 1,10-phenanthroline, 4,4-bipyridine, 4,7-diphenyl-1,10-phenanthroline (Bphen) and pyridine, are used as surface treatment agents for improving the electronic properties of perovskite materials. The results of the steady-state photoluminescence (PL), time resolved PL and hole-only devices made of CH3NH3PbBr3 thin films suggest that the traps are effectively passivated after post-deposition surface treatment with bidentate chelating ligands, including 1,10-phenanthroline and 4,4-bipyridine. Furthermore, the coordination capability of Bphen was suppressed which is probably due to its two additional phenyl groups, resulting in a steric hindrance effect. When compared with mono-dentate chelating pyridine, bidentate chelating ligands are more active in the current study. Finally, perovskite light-emitting diodes (PeLEDs) are fabricated and the devices exhibit a nearly doubled device efficiency after passivation with 1,10-phenanthroline. It is anticipated that the approach proposed here is a general method for improving the photonic properties of perovskite materials and the device performance of PeLEDs.
Virtual Screening of Conjugated Polymers for Organic Photovoltaic Devices Using Support Vector Machines and Ensemble Learning
(2019-01-01)
Chen, Fang-Chung
;
交大名義發表
;
光電工程學系
;
National Chiao Tung University
;
Department of Photonics
Herein, we report virtual screening of potential semiconductor polymers for high-performance organic photovoltaic (OPV) devices using various machine learning algorithms. We particularly focus on support vector machine (SVM) and ensemble learning approaches. We found that the power conversion efficiencies of the device prepared with the polymer candidates can be predicted with their structure fingerprints as the only inputs. In other words, no preliminary knowledge about material properties was required. Additionally, the predictive performance could be further improved by "blending" the results of the SVM and random forest models. The resulting ensemble learning algorithm might open up a new opportunity for more precise, high-throughput virtual screening of conjugated polymers for OPV devices.
Localized surface plasmon for enhanced lasing performance in solution-processed perovskites
(2016-09-05)
Kao, Tsung Sheng
;
Hong, Kuo-Bin
;
Chou, Yu-Hsun
;
Huang, Jiong-Fu
;
Chen, Fang-Chung
A promising method to promote the lasing performance of solution-processed organic-inorganic lead-halide perovskites has been demonstrated. With the adding Ag and PMMA thin films, the threshold excitation power for low-temperature lasing action in perovskites can be greatly reduced by over two orders of magnitude than that acquired in bare perovskite layers, ascribing to the strong exciton-plasmon coupling between the Ag and perovskite films. Also, the PMMA layer can be exploited to prevent the perovskite degradation from the hydrolysis in ambient environment, achieving long-lasting light-emitting performance. The advantages exhibited by the hybrid perovskite configuration would be very promising in making practical laser devices. (C) 2016 Optical Society of America
Metal Nanoparticle-Decorated Two-Dimensional Molybdenum Sulfide for Plasmonic-Enhanced Polymer Photovoltaic Devices
(2015-08-01)
Chuang, Ming-Kai
;
Yang, Shun-Shing
;
Chen, Fang-Chung
;
光電工程學系
;
Department of Photonics
Atomically thin two-dimensional (2D) transition metal dichalcogenides have also attracted immense interest because they exhibit appealing electronic, optical and mechanical properties. In this work, we prepared gold nanoparticle-decorated molybdenum sulfide (AuNP@MoS2) through a simple spontaneous redox reaction. Transmission electron microscopy, UV-Vis spectroscopy, and Raman spectroscopy were used to characterize the properties of the AuNP@MoS2 nanomaterials. Then we employed such nanocomposites as the cathode buffer layers of organic photovoltaic devices (OPVs) to trigger surface plasmonic resonance, leading to noticeable enhancements in overall device efficiencies. We attribute the primary origin of the improvement in device performance to local field enhancement induced by the effects of localized surface plasmonic resonance. Our results suggest that the metal nanoparticle-decorated two-dimensional materials appear to have great potential for use in high-performance OPVs.

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