1. H. H. J. Chang, T.W. Chen, J.W. Chen, W. C. Hong, W. C. Tsai, Y. F. Chen*, and G.Y. Guo,“Current and Strain-Induced Spin Polarization in InGaN/GaN Superlattices”, Phys. Rev. Lett.,98, 136403, (2007)

FIG. 2. (a) The theoretical effective Rashba coupling α_e = λ + a (eV Å) (О) and BIA coupling β (eV ų) (●) vs the inplane strain. (b) The theoretical spin Hall conductivity (σ^s _xy) (■) and the degree of circular polarization (CP) (▲) vs the in-plane strain. The in-plane electric field is applied in -y direction.

　

2. S.P. Fu, C.J. Yu, T.T. Chen, G.M. Hsu, M.J. Chen, L.C. Chen, K.S. Chen, and Y.F. Chen, “Anomalous optical properties of InN nanobelts: evidence of surface band bending and photoelastic effect”, Adv. Mater., 19 4524 (2007)

Schematic diagram of a) the crystallographic direction nanobelt, b) the band energy and surface electric field under low excitation intensity, and c) the band energy and surface electric field under high excitation intensity (E_C and E_V are the conduction and valence band, band edges, respectively, and F_n is the Fermi level in the conduction band).

　

3. Y.S. Lin, Y. Hung, H.Y. Lin, Y.H. Tseng, Y.F. Chen and, C.Y. Mou, “Photonic crystals from monodispersed lanthanide hydroxide silica”, Adv. Mater., 19, 577 (2007)

a) A transmission electron microscopy (TEM) image of 130 nm Tb(OH)₃@SiO₂ colloidal spheres, and b) a top-view field emission scanning electron microscopy (FESEM) image of a 3D PC crystallized from 190 nm Tb(OH)₃@SiO₂ core/shell spheres.

　

4. K.J. Wu, K.C. Chu, C.Y. Chao, Y.F. Chen*, C.W. Lai, C.C. Kang, C.Y. Chen, P.T. Chou, “CdS nanorods imbedded in liquid crystal cells for smart optoelectronic devices”, Nano Lett., 7, 1908 (2007)

Light-emitting devices: In the right direction

A device combining semiconductor nanorods with liquid crystals can produce tunable color emission via electric field control

Figure A color-tunable light-emitting device. The active region is a mixture of liquid crystals, CdSe nanorods and quantum dots (QDs) between indium tin oxide (ITO) electrodes. An applied electric field (E) rotates the liquid-crystal molecules and attached nanorods to change the color of emission. © 2010 Y.-F. Chen.

Electrons move freely along one-dimensional nanostructures such as nanorods, quantum wires or nanotubes, but their motion in the other two spatial directions is governed by quantum effects. One important implication of this behavior is that the optical response of these structures is strongly dependent on their orientation. A device that takes advantage of this phenomenon by using liquid crystals to rotate cadmium selenide (CdSe) nanorods has now been constructed by Yang-Fang Chen and co-workers at the National Taiwan University.

Chen and his co-workers mixed CdSe nanorods, just 25 nm long and 7 nm in diameter, with a liquid crystal known as E7 and CdSe quantum dots (QDs) — 5 nm-wide zero-dimensional structures in which electron motion is quantized in all three directions. To apply an electric field across the mixture while allowing any emission to be observed, the team injected the mixture between two glass slides coated with the transparent conductor indium tin oxide (ITO). The nanorods cling to the liquid-crystal molecules because the large surface areas involved generate a strong anchoring force. The liquid crystals — and therefore nanorods — can then be aligned in any direction by applying an electric field (Fig. 1). “We discovered that the physical properties of nanomaterials could be manipulated by an external bias due to the coupling between nanorods and liquid crystal molecules,” explains Chen.

The nanorods and QDs emit light when excited by a laser beam. The peak emission from the rods, which is yellow with a wavelength of 580 nm, is highly polarized because of the rod’s one-dimensional structure. The 650 nm red light from the dots, on the other hand, remains randomly polarized. This means that the contribution of the two light-emitting components — and thus the color of the emission — is dependent on which polarization, relative to the orientation of the nanorods, is measured.

Chen and his colleagues measured the optical output over a range of polarization angles and demonstrated that this approach enabled them to tune the color of light from the device. Chen hopes that further refinement of this approach, such as introducing photonic-crystal structures, will see an increase in device efficiency.

　

　

5. C.W. Hsu, A. Ganguly, C.H. Liang , C.T. Wu , Y.F. Chen, , et al., “Enhanced emission of (In, Ga) nitride nanowires embedded with self-assembled quantum dots”, Adv. Funct. Mater., 18, 938 (2008)

Proposed schematic illustration of type I-like band structure of a)–b) Ga-rich NWs (In-rich SAQD systems in Ga-rich matrix): a) retention of individual luminescence nature of both matrix and QDs at low temperature (T); b) same at high T: relaxation of carriers from high-energy level of matrix to low-energy level of QDs, domination of QD-luminescence. Corresponding illustration c)–e) for In-rich NWs (Ga-rich SAQD systems in In-rich matrix): c) trapping of excited electrons into the high-energy states of Ga-rich QDs at low T, domination of QD-luminescence; d) same at high T: relaxation of electrons via intermediate discrete energy-states between matrix and SAQDs, red shift of band-center and the lower-energy tail of PL; e) same at higher T: relaxation of excited holes, independent of its corresponding electrons, enhancement in intensity. The broad band nature of emission is due to the involvement of a set of QDs with inherent compositional fluctuation.

　

　

6. Y.P. Hsieh, H.Y. Chen, M.Z. Lin, S.C. Shiu, M.Y. Chern, X.T. Jia, H. J. Chang, H.M. Huang, S.C. Tseng, L.C. Chen, K.H. Chen, C.F. Lin, C.T. Liang and Y.F. Chen*, “Electroluminescence from ZnO/Si-nanotips light emitting diodes”, Nano Lett., 9 (5), pp 1839–1843 (2009)

Figure 1. Schematic diagrams showing the fabrication technique of our ZnO/Si-nanotips LED array.

Figure 2. (a) SEM picture of silicon nanotips after coating ZnO using pulsed laser deposition. (b) CL spectrum taken from the square region drawn in the middle of the nanotip array as shown in Figure 2(a). (c) TEM image of ZnO/Si-nanotips and (d) SAED pattern taken from the square region drawn in the middle of the nanotip array as shown in panel c. (e) PL spectra and (f) multiphonon Raman spectra of ZnO film coated on silicon nanotips and flat substrate.

7. Hang-Kuei Fu, Cheng-Liang Cheng, Chun-Hsiung Wang, Tai-Yuan Lin, Yang-Fang Chen, “Selective Angle Electroluminescence of Light-Emitting Diodes based on Nanostructured ZnO/GaN Heterojunctions”, Advanced Functional Materials, 19, 3471-3475(2009.11)

Scanning electron microscope images of ZnO nanobottles: a) on the side view embedded in ZEP520 taken at a tilt angle of 45℃ and b) on the top view. c) The top view of disordered ZnO nanowires. .

　

8. H. L. Tu, Y. S. Lin, H. Y. Lin, Y. Hung, L. W. Lo, Y. F. Chen, and C. Y. Mou, “In-vitro studies of functionalized mesoporous silica nanoparticles for photodynamic therapy”, Adv. Mater., 21, 172 (2009)

Flow cytometry analysis of A) the percentage and B) MFI of PpIX-MSNs-labeled HeLa cells; C) the confocal images of HeLa cells with 60mg mL^-1 PpIX-MSNs’ treatment. Our nanoparticles are those spots in red color, and the fluorescence signals of rhodamine phalloidin and DAPI are shown in green and blue color, respectively; D) dark cytotoxicity of cells incubated with PpIX-MSNs for 0 and 24 h, respectively.

　

　

9. Chun-Ying Huang, Di-Yan Wang, Chun-Hsiung Wang, Yung-Ting Chen, Yaw-Tyng Wang, You-Ting Jiang, Ying-Jay Yang, Chia-Chun Chen, and Yang-Fang Chen*, “Efficient Light Harvesting by Photon Downconversion and Light Trapping in Hybrid ZnS Nanoparticles/Si Nanotips Solar Cells”, ACS Nano 4, 10, 5849–5854 (2010)

Figure 1. Schematic diagram of Si nanotips solar cell structure with ZnS NPs.

10. Ming-Chung Wu, Jussi Hiltunen, Andras Sapi, Anna Avila, William Larsson, Hsueh-Chung Liao, Mika Huuhtanen, Geza Toth, Andrey Shchukarev, Noemi Laufer, Akos Kukovecz, Zoltan Konya, Jyri-Pekka Mikkola, Riitta Keiski, Wei-Fang Su, Yang-Fang Chen, Heli Jantunen, Pulickel M. Ajayan, Robert Vajtai*, Krisztian Kordas, “Nitrogen-Doped Anatase Nanofibers Decorated with Noble Metal Nanoparticles for Photocatalytic Production of Hydrogen ”, ACS nano, 5, 5025 (2011.06)

Hydrogen evolution from ethanol/water mixture (molar ratio 1:3) over parent and noble metal loaded (1.0 wt %) catalyst materials (100 mg each) under (a) UV-A (total UV power on the reactor ~1.54 W, λ(I_max) ~ 365 nm) and (b) UV-B (total UV power on the reactor ~1.46 W, λ(I_max) ~312 nm) irradiation. N₂ gas was bubbled through the reactor at a flow rate of 400 mL/min, serving also as a purging gas for the evolving gaseous products.

　

11. Hsueh-Chung Liao, Cheng-Si Tsao, Tsung-Han Lin, Meng-Huan Jao, Chih-Min Chuang, Sheng-Yong Chang, Yu-Ching Huang, Yu-Tsun Shao, Charn-Ying Chen, Chun-Jen Su, U-Ser Jeng, Yang-Fang Chen, and Wei-Fang Su*, “Nanoparticle Tuned Self-Organization of Bulk Heterojunction Hybrid Solar Cell with Enhanced Performance”, ACS Nano 6, 1657-1666 (2012)

We demonstrate here that the nanostructure of poly(3-hexylthiophene) and [6,6]-phenyl-C61-butyric acid methyl ester (P3HT/PCBM) bulk heterojunction (BHJ) can be tuned by inorganic nanoparticles (INPs) for enhanced solar cell performance. The self-organized nanostructural evolution of P3HT/PCBM/INPs thin films was investigated by using simultaneous grazing-incidence small-angle X-ray scattering (GISAXS) and grazing-incidence wide-angle X-ray scattering (GIWAXS) technique. Including INPs into P3HT/PCBM leads to (1) diffusion of PCBM molecules into aggregated PCBM clusters and (2) formation of interpenetrating networks that contain INPs which interact with amorphous P3HT polymer chains that are intercalated with PCBM molecules. Both of the nanostructures provide efficient pathways for free electron transport. The distinctive INP-tuned nanostructures are thermally stable and exhibit significantly enhanced electron mobility, external quantum efficiency, and photovoltaic device performance. These gains over conventional P3HT/PCBM directly result from newly demonstrated nanostructure. This work provides an attractive strategy for manipulating the phase-separated BHJ layers and also increases insight into nanostructural evolution when INPs are incorporated into BHJs.

　

　

12. Meng-Lin Lu, Chih-Wei Lai, Hsing-Ju Pan, Chung-Tse Chen, Pi-Tai Chou, Yang-Fang Chen*, “A Facile Integration of Zero- (I-III-VI Quantum Dots) and One- (Single SnO₂ Nanowire) Dimensional Nanomaterials: Fabrication of a Nanocomposite Photodetector with Ultrahigh Gain and Wide Spectral Response”, Nano Letters, 13, 1920−1927 (2013)

Demonstration of the high sensitivity under the illumination of photon energy smaller than the band gap of nanowire. The most important underlying mechanism arises from typeII band alignment between QDs and NW.

　

　

13. Hsueh-Chung Liao, Cheng-Si Tsao*, Yu-Tsun Shao, Sheng-Yung Chang, Yu-Ching Huang, Chih-Min Chuang, Tsung-Han Lin, Charn-Ying Chen, Chun-Jen Su, U-Ser Jeng, Yang-Fang Chen, Wei-Fang Su*, “Bi-hierarchical nanostructures of donor-acceptor copolymer and fullerene for high efficient bulk heterojunction solar cells”, Energy & Environmental Science, 6, 1938-1948 (2013)

Schematic diagrams of 3-D nanostructures of PCPDTBT/PCBM blend films processed (a) without DIO, i.e. BL78_w/o DIO and (b) with 3% DIO, i.e. BL78_3% DIO. The BL78_w/o DIO consists of PCPDTBT amorphous chains and PCBM fractal aggregation (R_g-PCBM ~ 137 nm, D_PCBM ~ 1.5) with PCBM molecule as the primary particle (2R_PCBM ~ 1 nm). The BL78_3% DIO films includes PCBM fractal aggregation (R_g-PCBM ~ 15 nm, D_PCBM ~ 3.0) and PCPDTBT fractal aggregation (R_g-PCPDTBT ~ 125 nm, D_PCPDTBT ~ 3.0) that is formed by PCPDTBT primary particles (2R_PCPDTBT ~ 20 nm) which comprise PCPDTBT basic crystals (L ~ 5 nm).

　

　

　

14. Y.C. Lai, J.Y. Chen, T.C. Chang, Y.T. Yang, F.C. Hsu, and Y.F. Chen*, “Transferable and Flexible Label-Like Macromolecular Memory on Arbitrary Substrates with High Performance and a Facile Methodology ”, Advanced Materials, 25, 2733–2739 (2013)

15. Che-Wei Chang, Wei-Chun Tan, Meng-Lin Lu, Tai-Chun Pan, Ying-Jay Yang, Yang-Fang Chen*, “Graphene/SiO₂/p-GaN Diodes: An Advanced Economical Alternative for Electrically Tunable Light Emitters”, Advanced Functional Materials, 23, 4043-4048 (2013)

a) Schematics of graphene/SiO₂/p-GaN MIS-LED and AFM image (inset) of the graphene electrode and photograph of the device. b) EL spectra of graphene/SiO₂/p-GaN MIS-LEDs under forward bias at different injection currents at room temperature. The inset shows a photograph of the light emission from MIS-LEDs under forward bias. 

　

　

　

16. J. Y. Chen, C. Y. Ho, M. L. Lu, L. J. Chu, K. C. Chen, S. W. Chu, W. Chen, C. Y. Mou, and Y. F. Chen*, “Efficient Spin-Light Emitting Diodes Based on InGaN/GaN Quantum Disks at Room Temperature: A New Self-Polarized Paradigm”, Nano Letters, Nano Letters, 14, 3130 (2014)

Band diagram of (a) spin-down and (b) spin-up electrons in InGaN and Fe₃O₄. It enables selective transfer of spin polarized electrons and holes and leads to the enhanced output spin polarization of LED.

　

　

　

18. Ju-Ying Chen, Tong-Ming Wong, Che-Wei Chang, Chen-Yuan Dong, and Yang-Fang Chen* “Self-polarized spin-nanolasers”, Nature Nanotechnology, 9, 845 (2014)

Schematics of band alignment of spin-down and spin-up electrons between GaN and Fe₃O₄. a, Band alignment of spin-down electrons between GaN and Fe₃O₄. The imperfection of spin orientation of the electrons at the Fermi energy of Fe₃O₄ is shown explicitly to reflect the true situation. b, Band alignment of spin-up electrons between GaN and Fe₃O₄. Owing to the population imbalance of spin alignment, the recombination of electron and hole generates spin-polarized emissions. E_F, Fermi energy; up and down arrows, spin orientation of the electrons; shaded areas, energy states occupied by electrons; HH⁺, heavy holes; LH⁺, light holes.

19. Tzu-Min Sun, Cih-Su Wang, Chi-Shiun Liao, Lin-Shih Yao, Packiyaraj Perumal, Chia-Wei Chiang, and Yang-Fang Chen*, “Stretchable Random Lasers with Tunable Coherent Loops”, ACS Nano, 9, 12436-12441 (2015)

(a) Lasing action before stretching. Lasing action of stretching length (b) 10%, (c) 20%, and (d) 30%. (e) Detected times versus lasing mode number before stretching. Detected times versus lasing mode number of stretching length (f) 10%, (g) 20%, and (h) 30%.

　

　

　

20. Cih-Su Wang, Chuan-Hsien Nieh, Tai-Yuan Lin andYang-Fang Chen*, “Electrically driven random laser memory”, Advanced Functional Materials, 25, 4058-4063 (2015)

The first proof-of-concept presentation of random laser memory possesses several advantages of dual memory and lasing functions, which enables to open up new avenues to practical applications, such as light emitting memories for electrical and optical communication.

　

　

　

21. Golam Haider, Muhammad Usman, Tzu-Pei Chen, Packiyaraj Perumal, Kuang-Lieh Lu*, and Yang-Fang Chen*, “Electrically Driven White Light Emission from Intrinsic Metal-Organic Framework”, ACS Nano, 10, 8366 (2016)

Cross-sectional scanning electron microscopy image and schematic diagram of the device, where a pn junction is formed by a 140 nm coating of ZnO and a ~940 nm coating of the MOF on top of a 100 nm Ag film. p-Type Si/SiO₂ was used as the substrate. Graphene was used as the top electrode.

22. Packiyaraj Perumal, Rajesh Kumar Ulaganathan, Raman Sankar, Yu-Ming Liao, Tzu-Min Sun, Ming-Wen Chu, Fang Cheng Chou, Yit-Tsong Chen, Min-Hsiung Shih, Yang-Fang Chen*, “Ultra-Thin Layered Ternary Single Crystals [Sn(SxSe1-x)₂] with Bandgap Engineering for High Performance Phototransistors on Versatile Substrates”, Advanced Functional Materials, 26, 3630 (2016)

I V characteristics of few-layered SnSSe phototransistor. a) The schematic illustration represents a few-layered SnSSe phototransistor. b) Optical microscope image of 6 nm thin SnSSe phototransistor separated by 14 μm gap with two Cr/Au electrode. c) The linear I_ds-V_ds characteristic curve measured at different V_g from -40 to 40 V, represents ohmic behavior. d) I_ds-V_g characteristic curve measured at V_g from -80 to 80 V at V_ds = 10 V (under dark and laser power of 310.82 mWcm^-2 ).

23. Golam Haider, Prathik Roy, Chia-Wei Chiang, Wei-Chun Tan, Yi-Rou Liou, Huan-Tsung Chang, Chi-Te Liang, Wei-Heng Shih, Yang-Fang Chen*, “Electrical-Polarization-Induced Ultrahigh Responsivity Photodetectors Based on Graphene and Graphene Quantum Dots”, Advanced Functional Materials, 26, 620 (2016)

Hybrid quantum dot-graphene photodetectors have recently attracted substantial interest owing to their remarkable performance and low power consumption. However, the performance of the device greatly depends on the interfacial states and photogenerated screening field. As a consequence, the sensitivity is limited and the response time is relatively slow. In order to circumvent these challenges, we have designed a composite graphene and graphene quantum dot (GQD) photodetector on Lead Zirconate Titanate (Pb(Zrr_0.2Ti_0.8)O₃) (PZT) substrates to form a ultra-sensitive photodetector over a wide range of illumination power. Under 325 nm UV light illumination, the device shows sensitivity as high as 4.06x10⁹ AW^-1, which is 120 times higher than reported sensitivity of the same class of devices. Plant derived GQD has a broad range of absorptivity and is an excellent candidate for harvesting photons generating electron-hole pairs. Intrinsic electric field from PZT substrate separates photogenerated electron-hole pairs as well as provides the built-in electric field that causes the holes to transfer to the underlying graphene channel. The composite structure of graphene and GQD on PZT substrate therefore produces a simple, stable, and highly sensitive photodetector over a wide range of power with short response time, which shows a way to obtain high performance optoelectronic devices.

24. Ying-Chih Lai, Bo-Wei Ye, Chun-Fu Lu, Chien-Tung Chen, Meng-Huan Jao, Wei-Fang Su, Wen-Yi Hung, Tai-Yuan Lin, Yang-Fang Chen*, “Extraordinarily Sensitive and Low-Voltage Operational Cloth-Based Electronic Skin for Wearable Sensing and Multifunctional Integration Uses: A Tactile Induced Insulating-to-Conducting Transition”, Advanced Functional Materials 23, 1286-1295 (2016)

(a) Real-time current responses to different mechanical forces including touching, bending, twisting, and stretching forces. (b) Real-time current responses to different sentences spoken by the tester. The inset shows the photographs of as-prepared device attached onto the collar of shirt worn on the tester. (c) Real-time current responses to different hand motion.

25. Han-Wen Hu, Golam Haider, Yu-Ming Liao, Pradip Kumar Roy, Rini Ravindranath, Huan-Tsung Chang, Cheng-Hsin Lu, Chang-Yang Tseng, Tai-Yung Lin, Wei-Heng Shih, Yang-Fang Chen*, “Wrinkled 2D Materials: A Versatile Platform for Low-Threshold Stretchable Random Lasers”, Advanced Materials, 29, 1703549 (2017)

Schematic of wrinkled 2D materials decorated with quantum dots, which is very useful to serve an excellent platform for stretchable random laser. In particular, rGO shows the best performance.

26. Xiaoyu Shi, Yu-Ming Liao , Hsia-Yu Lin, Po-Wei Tsao, Meng-Jer Wu, Shih-Yao Lin, Hsiu-Hao Hu, Zhaona Wang, Tai-Yuan Lin, Ying-Chih Lai, and Yang-Fang Chen*, “Dissolvable and Recyclable Random Lasers”, ACS Nano, 11, 7600-7607 (2017)

Recycling and reusable performance of the dissolvable and recyclable random laser (DRRL). (a) Schematic illustration of the recycling process. (b) Emission spectra with different cycle index. (c) Corresponding evolution of emission peak intensity and threshold as a function of recycling times.

27. Wei-Chun Tan, Yu-Chi Chen, Yi-Rou Liou, Han-Wen Hu, Mario Hofmann* and Yang-Fang Chen*, “An Arbitrary Color Light Emitter”, Advanced Materials, 29, 1604076 (2017)

(a) Biasing conditions (VSD,VGS) to access different points in the chromaticity diagram, (inset) schematic view of the vertical light emitting transistor and quantum dot film structure, (b) Photographs of a device with and without QDs under different biasing conditions and the corresponding chromaticity points, (c) EL spectrum of QD/graphene/SiO₂/p-GaN LEDs at VSD = -12 V and VGS = -5 V, (inset) photograph of demonstrated white light emission under those biasing conditions.

28. Golam Haider, Rini Ravindranath, Tzu-Pei Chen, Prathik Roy, Pradip Kumar Roy, Shu-Yi Cai, Huan-Tsung Chang and Yang-Fang Chen*,“Dirac point induced ultralow-threshold laser and giant optoelectronic quantum oscillations in graphene-based heterojunctions”, Nature Communications, 8, 256 (2017)

All-graphene sandwich device exhibits quantum oscillations of current. a. Schematic representation of the device. The top graphene (GrT) and bottom graphene (GrB) serve as the carrier injection layers to the GQDs. b. Current oscillations due to resonant tunneling of electrons for positive bias. The inset shows the respective positions of Fermi energy (black dot lines) of both graphene at different regions. c. The energy band diagram of different layers without application of external bias. The zero bias misalignment of Dirac point arises from the substrate effect. d. The band structure with the application of positive bias shows a resonance tunneling of electrons. The recombination occurs due to the presence of holes in the valence band. e. Magnified I–V near the Dirac point. The yellow and green colors in the bottom graphene show the position of nearly zero effective mass (m eff) zone for the carriers. Inset color bars are cartoon diagrams representing the variation of m eff around the Dirac point. f. Oscillation of current under negative bias. The I–V shows a π phase difference of current oscillations in opposite bias. The inset depicts the position of Fermi energy of the graphene at different bias voltage. g. The energy band diagram of the composite under reverse bias.

29. Golam Haider*, Hung-I Lin , Kanchan Yadav, Kun-Ching Shen, Yu-Ming Liao, Han-Wen Hu, Pradip Kumar Roy, Krishna Prasad Bera, Kung-Hsuan Lin, Hsien-Ming Lee, Yit-Tsong Chen, Fu-Rong Chen, and Yang-Fang Chen*, “A Highly-Efficient Single Segment White Random Laser”, ACS Nano, 12, 11847-11859 (2018)

Schematic illustration of the device structure. The upconversion nanoparticles (UCNPs) were coated on top of HMM samples. Under the excitation of continuous 980 nm infrared laser, the emission spectrum produces multiple emission lines covering visible range. As a result, white laser action is observed. Printed with the permission from Janis Liu.

30. Monika Kataria, Kanchan Yadav, Shu-Yi Cai, Yu-Ming Liao, Hung-I Lin, Tien Lin Shen, Ying-Huan Chen, Yit-Tsong Chen*, Wei-Hua Wang, Yang-Fang Chen*, “Highly Sensitive, Visible Blind, Wearable, and Omnidirectional Near-Infrared Photodetectors”, ACS Nano, 12, 9596-9607(2018)

(a) Schematic diagram of the UCNPs/graphene hybrid micropyramidal structure photodetector. (b) (i) Cross-sectional SEM image of the micropyramidal structure PDMS. (ii, iii) Lateral SEM images of the micropyramidal structure PDMS with graphene transferred over it. (iv) Lateral SEM image of the micropyramidal structure PDMS with UCNPs spin coated over it uniformly.

31. Krishna Prasad Bera, Golam Haider, Muhammad Usman, Pradip Kumar Roy, Hung-I Lin, Yu-Ming Liao, Christy Roshini Paul Inbaraj, Yi-Rou Liou, Monika Kataria, Kuang-Lieh Lu, Yang-Fang Chen*, “Trapped Photons Induced Ultrahigh External Quantum Efficiency and Photoresponsivity in Hybrid Graphene/Metal-Organic Framework Broadband Wearable Photodetectors”, Adv. Funct. Mater., 1804802 (2018))

(a) Schematic diagram of the photodetector. (b) SEM image of ripple structure. (c) Transient photoresponse of the device current under the illumination of 325 nm laser with power 10 nW at the bias voltage of 0.1 V. (d) Energy band diagram of the graphene−MOF hybrid photodetector before and after the illumination of photons and applying an external bias.

32. Yun-Tzu Hsu, Chia-Tse Tai, Hsing-Mei Wu, Cheng-Fu Hou, Yu-Ming Liao, Wei-Cheng Liao, Golam Haider, Yung-Chi Hsiao, Chi-Wei Lee, Shu-Wei Chang, Ying-Huan Chen, Min-Hsuan Wu, Rou-Jun Chou, Krishna Prasad Bera, Yen-Yu Lin, Yi-Zih Chen, Monika Kataria, Shih-Yao Lin, Christy Roshini Paul Inbaraj, Wei-Ju Lin, Wen-Ya Lee, Tai-Yuan Lin, Ying-Chih Lai*, Yang-Fang Chen*, “Self-Healing Nanophotonics: Robust and Soft Random Lasers”, ACS Nano, 13, 8977-8985 (2019)

Soft and self-healable random lasers (SSRLs).

33. T. N. Lin, S. R. M. Santiago, S. P. Caigas, C. T. Yuan, T. Y. Lin, J. L. Shen* and Y. F. Chen, “Many-body effects in doped WS2 monolayer quantum disks at room temperature”, npj 2D Materials and Applications, 3, 46 (2019)

Band-gap analysis. a. E_con and E_g of the WS₂ MQDs with different carrier densities. b. Schematic diagram showing the doping effect in the band structures of WS₂ MQDs.

34. Krishna Prasad Bera, Golam Haider, Yu-Ting Huang, Pradip Kumar Roy, Christy Roshini Paul Inbaraj, Yu-Ming Liao, Hung-I Lin, Cheng-Hsin Lu, Chun Shen, Wan Y Shih, Wei-Heng Shih, Yang-Fang Chen*“Graphene Sandwich Stable Perovskite Quantum-Dot Light-Emissive Ultrasensitive and Ultrafast Broadband Vertical Phototransistors”, ACS Nano, 13, 12540-12552 (2019)

Schematic design of a vertical phototransistor, which can serve a highly sensitive photodetector and light emitter.

35. Guan‐Zhang Lu, Meng‐Jer Wu, Tzu‐Neng Lin, Chi‐Yuan Chang, Wei‐Ling Lin, Yi Ting Chen, Chen‐Fu Hou, Hao‐Jan Cheng, Tai‐Yuan Lin*, Ji‐Lin Shen*, Yang‐Fang Chen*, “Electrically Pumped White‐Light‐Emitting Diodes Based on Histidine‐Doped MoS₂ Quantum Dots”, Small, 15, 1901908 (2019)

(a) Device structure of histidine-doped MoS₂ based QD-WLEDs. (b) Cross-sectional SEM image of histidine-doped MoS₂ based QD-WLEDs. (c) Current versus driving voltage (I-V) characteristics for the histidine-doped MoS₂ based QD-WLEDs device; inset is the optical picture of WLED.

36. Samik Jhulki, Jeehong Kim, In-Chul Hwang, Golam Haider, Jiyong Park, Ji Young Park, Yeonsang Lee, Wooseup Hwang, Ajaz Ahmed Dar, Barun Dhara, Sang Hoon Lee, Juho Kim, Jin Young Koo, Moon Ho Jo, Chan-Cuk Hwang, Young Hwa Jung, Youngsin Park, Monika Kataria, Yang-Fang Chen, Seung-Hoon Jhi*, Mu-Hyun Baik*, Kangkyun Baek*, Kimoon Kim*, “Solution-Processable, Crystalline π-Conjugated Two-Dimensional Polymers with High Charge Carrier Mobility”, Chem, 6, 2035-2045 (2020)

37. Tien-Lin Shen, Han-Wen Hu, Wei-Ju Lin, Yu-Ming Liao, Tzu-Pei Chen, Yu-Kuang Liao, Tai-Yuan Lin, Yang-Fang Chen*, “Coherent Förster resonance energy transfer: A new paradigm for electrically driven quantum dot random lasers”, Science Advances, 6, eaba1705 (2020)

Structure of the QD random laser device.(A) Schematic of the QD random laser device. (B) Side-view SEM image of the device structure showing each layer is well deposited. Scale bar, 200 nm. (C) Schematic illustration of CFRET. (D) SEM topography of the mixture QD film. Scale bar, 100 nm. The inset shows the real photo of the red-light emission from the QD random laser device.

38. Rapti Ghosh, Hung‐I Lin, Yu‐Siang Chen, Mukesh Singh, Zhi‐Long Yen, Shengkuei Chiu, Hsia‐Yu Lin, Krishna P Bera, Yu‐Ming Liao, Mario Hofmann, Ya‐Ping Hsieh, Yang‐Fang Chen*, “QD/2D Hybrid Nanoscrolls: A New Class of Materials for High‐Performance Polarized Photodetection and Ultralow Threshold Laser Action”, Small, 16, 2003944 (2020)

a) High-resolution TEM (HRTEM) image of the pristine WS₂-NS (inset: zoomed in image of the wall). b) Selected-area diffraction pattern (SAED) of the individual WS₂-NS. c) (HRTEM) image of WS₂-NS hybridized with CdSe-ZnS core-shell QDs and corresponding d) SAED pattern of an individual hybridized WS2-NS.

39. Shu-Yuan Chiang, Yueh-Yuan Li, Tien-Lin Shen, Mario Hofmann*, Yang-Fang Chen*, “2D Material-Enabled Nanomechanical Bolometer”, Nano Lett., 20, 2326 (2020)

40. Hung-I Lin, Chun-Che Wang, Kun-Ching Shen, Mikhail Y Shalaginov, Pradip Kumar Roy, Krishna Prasad Bera, Monika Kataria, Christy Roshini Paul Inbaraj, Yang-Fang Chen*, “Enhanced laser action from smart fabrics made with rollable hyperbolic metamaterials”, npj Flexible Electronics, 4, 1-10 (2020)

41. Chi‐Yuan Chang, Hsin‐Hsiang Huang, Hsinhan Tsai, Shu‐Ling Lin, Pang‐Hsiao Liu, Wei Chen, Fang‐Chi Hsu, Wanyi Nie*, Yang‐Fang Chen*, Leeyih Wang*, “Facile Fabrication of Self‐Assembly Functionalized Polythiophene Hole Transporting Layer for High Performance Perovskite Solar Cells”, Advanced Science, 8, 2002718 (2021)

Spin coating and self-assembly route to prepare PEDOT:PSS and P3HT-COOH on ITO substrates. Schematic illustration for spin coated polymer thin film of b) PEDOT:PSS (top), P3HT-COOH (bottom), and c) self-assembled P3HT-COOH. The insets are the contact angle images of deionized water on fabricated HTMs from (b)–(c). d) Contact angle plot with HTMs with different fabrication methods. e) Surface SEM images and f) GIWAXS patterns showing the evolution of the three perovskite grain types under different HTMs. g) GIWAXS line-cut from f with their FWHM on the characteristic peaks of (110) plane in MAPbI3 on three different HTMs. Zoom-in profiles for h) (110) and i) (200) peaks. j) Integral breadth (IB) analysis using Halder–Wagner plots, where β is the integral breadth of the diffraction peak and S is defined as S = 2 s i n θ λ.

42. Meng-Jer Wu, Shang-Cheng Wu, Tien-Lin Shen, Yu-Ming Liao, and Yang-Fang Chen*, “Anderson Localization Enabled Spectrally Stable Deep-Ultraviolet Laser Based on Metallic Nanoparticle Decorated AlGaN Multiple Quantum Wells”, ACS Nano, 15, 330-337 (2021)

Schematic of the formation of Anderson localization induced coherent closed loops due to multiple scattering in the AlGaN MQWs devices, which enables to generate spectrally stable deep UV laser.

43. Christy Roshini Paul Inbaraj, Roshan Jesus Mathew, Rajesh Kumar Ulaganathan, Raman Sankar, Monika Kataria, Hsia Yu Lin, Yit-Tsong Chen, Mario Hofmann*, Chih-Hao Lee, Yang-Fang Chen*, “A Bi-Anti-Ambipolar Field Effect Transistor”, ACS Nano, 15, 8686-8693 (2021)