Browsing by Author "Shen, Tien-Lin"

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Breakthrough to Non-Vacuum Deposition of Single-Crystal, Ultra-Thin, Homogeneous Nanoparticle Layers: A Better Alternative to Chemical Bath Deposition and Atomic Layer Deposition
(2017-04-01)
Liao, Yu-Kuang
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Liu, Yung-Tsung
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Hsieh, Dan-Hua
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Shen, Tien-Lin
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Hsieh, Ming-Yang
Most thin-film techniques require a multiple vacuum process, and cannot produce high-coverage continuous thin filmswith the thickness of a fewnanometers on rough surfaces. We present a new "paradigm shift" non-vacuum process to deposit high-quality, ultra-thin, single-crystal layers of coalesced sulfide nanoparticles (NPs) with controllable thickness down to a few nanometers, based on thermal decomposition. This provides high-coverage, homogeneous thickness, and large-area deposition over a rough surface, with little material loss or liquid chemical waste, and deposition rates of 10 nm/min. This technique can potentially replace conventional thin-film deposition methods, such as atomic layer deposition (ALD) and chemical bath deposition (CBD) as used by the Cu(In, Ga) Se2 (CIGS) thin-film solar cell industry for decades. We demonstrate 32% improvement of CIGS thin-film solar cell efficiency in comparison to reference devices prepared by conventional CBD deposition method by depositing the ZnS NPs buffer layer using the new process. The new ZnS NPs layer allows reduction of an intrinsic ZnO layer, which can lead to severe shunt leakage in case of a CBD buffer layer. This leads to a 65% relative efficiency increase.
Bridging the "green gap" of LEDs: giant light output enhancement and directional control of LEDs via embedded nano-void photonic crystals
(2016-01-01)
Tsai, Yu-Lin
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Liu, Che-Yu
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Krishnan, Chirenjeevi
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Lin, Da-Wei
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Chu, You-Chen
Green LEDs do not show the same level of performance as their blue and red cousins, greatly hindering the solid-state lighting development, which is the so-called "green gap". In this work, nano-void photonic crystals (NVPCs) were fabricated to embed within the GaN/InGaN green LEDs by using epitaxial lateral overgrowth (ELO) and nano-sphere lithography techniques. The NVPCs act as an efficient scattering back-reflector to outcouple the guided and downward photons, which not only boost the light extraction efficiency of LEDs with an enhancement of 78% but also collimate the view angle of LEDs from 131.5 degrees to 114.0 degrees. This could be because of the highly scattering nature of NVPCs which reduce the interference giving rise to Fabry-Perot resonance. Moreover, due to the threading dislocation suppression and strain relief by the NVPCs, the internal quantum efficiency was increased by 25% and droop behavior was reduced from 37.4% to 25.9%. The enhancement of light output power can be achieved as high as 151% at a driving current of 350 mA. Giant light output enhancement and directional control via NVPCs point the way towards a promising avenue of solid-state lighting.
Enhance Current Density and Power Conversion Efficiency in Solar Cells by Using Luminescent Downshifting Phosphors
(2014-01-01)
Han, Hau-Vei
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Lin, Chien-Chung
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Lin, Wein-Yi
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Tsai, Yu-Lin
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Shen, Tien-Lin
The silicate phosphor on the surface of GaAs solar cell are demonstrated to have promising potential for efficient solar spectrum utilization. The phosphor is a common utilized material in white light LED package, so the cost of phosphor is relatively low and the stability is good. The solar cells showed an enhancement of 22.8% in short-circuit current density and approximately 25.3% in power conversion efficiency when coated with silicate phosphor particles. The current analyses and experiments conclude that the phosphor particles not only play as luminescent downshifting centers in the ultraviolet region but also serve as an anti-reflection coating for enhancing the light absorption in the overall spectral response of external quantum efficiency.
Positioning Effect of Type-II GaSb/GaAs Quantum Ring Layer on Solar Cell Performances
(2015)
Hsu, Shun-Chieh
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Chen, Yin-Han
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Chen, Hsuan-An
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Lin, Shih-Yen
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Shen, Tien-Lin
In this work, we demonstrate the positioning effect of the type-II quantum ring (QR) on the solar cell efficiencies. The QR layer was placed in either p-type or n-type region to test its effect on the performance. Under one Sun condition, the one with p-type QR layer has better efficiency and open-circuit voltage. But this advantage loses quickly when the sunlight is concentrated over 20 times. From the concentrated sunlight measurement, the sample with QR layer in the n-type region can sustain the V-oc reduction until 80 Suns.
Seeing pressure in color based on integration o highly sensitive pressure sensor and emission tunable light emitting diode
(2019-11-25)
Shen, Tien-Lin
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Chen, Chien-Tung
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Liao, Yu-Kuang
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Su, Teng-Yu
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Liu, Che-Yu
We demonstrate a highly sensitive, low-cost, environmental-friendly pressure sensor derived from a wool-based pressure sensor with wide pressure sensing range using wool bricks embedded with a Ag nano-wires. The easy fabrication and light weight allow portable and wearable device applications. Wth the integration of a light-emitting diode possessing multi-wavelength emission, we illustrate a hybrid multi-functional LED-integrated pressure sensor that is able to convert different applied pressures to light emission with different wavelengths. Due to the high sensitivity of the pressure sensor, the demonstration of acoustic signal detection has also been presented using sound of a metronome and a speaker playing a song. This multi-functional pressure sensor can be implemented to technologies such as smart lighting, health care, visible light communication (VLC), and other internet of things (IoT) applications. (C) 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement
Self-Powered, Self-Healed, and Shape-Adaptive Ultraviolet Photodetectors
(2020-02-26)
Tsai, Meng-Shian
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Shen, Tien-Lin
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Wu, Hsing-Mei
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Liao, Yu-Ming
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Liao, Yu-Kuang
The emergence of self-healing devices in recent years has drawn a great amount of attention in both academics and industry. Self-healed devices can autonomically restore a rupture as unexpected destruction occurs, which can efficiently prolong the life span of the devices; hence, they have an enhanced durability and decreased replacement cost. As a result, integration of wearable devices with self-healed electronics has become an indispensable issue in smart wearable devices. In this study, we present the first self-powered, self-healed, and wearable ultraviolet (UV) photodetector based on the integration of agarose/poly(vinyl alcohol) (PVA) double network (DN) hydrogels, which have the advantages of good mechanical strength, self-healing ability, and tolerability of multiple types of damage. With the integration of a DN hydrogel substrate, the photodetector enables 90% of the initial efficiency to be restored after five healing cycles, and each rapid healing time is suppressed to only 10 s. The proposed device has several merits, including having an all spray coating, self-sustainability, biocompatibility, good sensitivity, mechanical flexibility, and an outstanding healing ability, which are all essential to build smart electronic systems. The unprecedented self-healed photodetector expands the future scope of electronic skin design, and it also offers a new platform for the development of next-generation wearable electronics.
Ultrahigh-Performance Self-Powered Flexible Photodetector Driven from Photogating, Piezo-Phototronic, and Ferroelectric Effects
(1970-01-01)
Shen, Tien-Lin
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Chu, Yu-Wei
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Liao, Yu-Kuang
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Lee, Wen-Ya
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Kuo, Hao-Chung
Owing to the need for dynamic, real-time, and on-site data collection in internet of things applications, the realization of ultra-sensitive sensing networks with self-powered, flexible, and lightweight devices has become an important issue for the development of sensor systems. In this work, a novel, high-performance, self-powered photodetector is achieved through the combination of photogating, piezo-phototronic, and ferroelectric effect by incorporating a ferroelectric thin film of poly(vinylidene fluoride-co-trifluoroethylene) in a rationally designed device structure with suitable band alignment, which can modulate carrier transport behavior at the interface due to the internal electric field produced by light illumination, external strain, or voltage-poled dipole. This enables photocurrent and overall device performance to improve significantly. The unprecedented photodetector presented in this study has several merits, including mechanical flexibility and light weight that allow it to adapt to arbitrary surface topology; additionally, its self-powering capability and high reliability are urgently needed for the demanding functionality of devices for the development of next-generation optoelectronic devices, spanning from wearable communication to unattended harsh environments with a human-friendly interface.