Broadband Absorption Enhancement in µc-Si:H Thin-Film Solar Cells Based on Silver Nanoparticle Arrays

Shi-E Yang,Ping Liu,Dong Ding,Qiaoneng Guo,Yong-Sheng Chen 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2017 NANO Vol.12 No.3

The thin-film solar cell structure with a broadband absorption enhancement is reported. We designed spherical silver (Ag) nanoparticle arrays on or embedded partially into indium tin oxide (ITO) layer of the hydrogenated microcrystalline silicon (µc-Si:H) thin-film solar cells. The geometrical parameters, such as nanoparticle radius (R), array period (P) and ITO layer thickness (d) are optimized by using the finite element method (FEM). The numerical results show that the key parameter that influences the integrated absorption is period/radius ratio (P/R) for Ag nanoparticle arrays. Embedding nanoparticle arrays partially into ITO layer with the appropriate thickness can improve broadband light-trapping. The optimized structure shows 50.1% enhancement in the integrated absorption compared to the reference cell when P = 500 nm, R = 100 nm and d = 70 nm. Furthermore, physical mechanisms of absorption enhancement in different wavelength range are discussed according to the electrical field amplitude distributions in the solar cells.

Intrinsic rotation reversal, non-local transport, and turbulence transition in KSTAR L-mode plasmas

Shi, Y.J.,Kwon, J.M.,Diamond, P.H.,Ko, W.H.,Choi, M.J.,Ko, S.H.,Hahn, S.H.,Na, D.H.,Leem, J.E.,Lee, J.A.,Yang, S.M.,Lee, K.D.,Joung, M.,Jeong, J.H.,Yoo, J.W.,Lee, W.C.,Lee, J.H.,Bae, Y.S.,Lee, S.G.,Yo International Atomic Energy Agency 2017 Nuclear fusion Vol.57 No.6

<P>Experiments of electron cyclotron resonance heating (ECH) power scan in KSTAR tokamak clearly demonstrate that both the cutoff density for non-local heat transport (NLT) and the threshold density for intrinsic rotation reversal can be determined by the collisionality. We demonstrate that NLT can be affected by ECH, and the intrinsic rotation direction follows the changes of NLT. The cutoff density of NLT and threshold density for rotation reversal can be significantly increased by ECH. The poloidal flow of turbulence in core plasma is in the electron and the ion diamagnetic direction in ECH plasmas and high density OH plasma, respectively. The auto-power spectra of density fluctuation are almost the same in the outer region for both ECH and OH plasmas. On the other hand, the divergence in density fluctuation spectra at high frequency range between OH and ECH plasma is clearly observed in core region. The features of linear confinement and saturated confinement also appeared in ECH plasma, which is similar to the linear ohmic confinement (LOC) mode and saturate ohmic confinement (SOC) mode. All these observations in macroscopic parameters and micro fluctuations suggest a possible link between the macro phenomena and the structural changes in turbulence mode.</P>

Hardening steels by the generation of transient phase using additive manufacturing

Huang, E-Wen,Lee, Soo Yeol,Jain, Jayant,Tong, Yang,An, Ke,Tsou, Nien-Ti,Lam, Tu-Ngoc,Yu, Dunji,Chae, Hobyung,Chen, Shi-Wei,Chen, Shih-Min,Chou, Hung-Sheng Elsevier 2019 Intermetallics Vol.109 No.-

<P><B>Abstract</B></P> <P>In the present work, the tensile properties of 15–5 PH steel fabricated by selective laser melting (SLM) were examined with respect to the transient austenite phase. Compared with the 8%-transient-phase sample, the 18%-transient-phase one shows higher ultimate tensile strength and relatively low yield strength, as well as hardening behavior. We conducted <I>in-situ</I> neutron-diffraction study to examine the microstructure evolution for mechanistic understanding. After applying the external load, most non-equilibrium, retained austenite in the 8%-transient-phase sample transforms before the yield strength, whereas in the 18%-transient-phase sample only 50% of the austenite transforms. Accompanying with the phase transformation, a decrease in the dislocation density and the dislocation strain energy-assisted phase transformation of the ferrite phase are found in the 8%-transient-phase sample even before yielding, which, however, is not the case in the 18%-transient-phase sample. The study demonstrates the SLM enables tuning the amount of transient-phase ratio and coherency between phases to realize a mechanical property control for additive manufactured steel.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The tensile behavior was examined for 8%- and 18%-transient-phase additive manufacturing steels using in-situ neutron diffraction. </LI> <LI> The 18%-transient-phase sample exhibited higher ultimate tensile strength and low yield strength. </LI> <LI> The 18%-transient-phase specimen with more non-equilibrium γ-phase revealed a more profound strain hardening effect. </LI> </UL> </P>

Fabricating Cu2O-CuO submicron-cubes for efficient catalytic CO oxidation: The significant effect of heterojunction interface

Yiyu Shi,Leilei Xu,Mindong Chen,Bo Yang,Ge Cheng,Cai-e Wu,Zhichao Miao,Ning Wang,Xun Hu 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.105 No.-

In this work, the uniform Cu2O submicron-cubes were facilely synthesized by liquid phase reductionmethod. Then, the Cu2O submicron-cubes were further oxidized into Cu2O-CuO heterojunction with tunableCu2+/Cu+ ratios and CuO submicron-cubes by controlling the calcination temperature. The phasetransition period during calcination was real-time monitored by the in-situ XRD and in-situ DRIFTS. The obtained materials were investigated as the catalysts of CO oxidation. The results revealed thatthe Cu2O-CuO heterojunction catalysts performed much higher catalytic activities than the Cu2O andCuO counterparts. Because the synergistic effect of the heterojunction (Cu2+/Cu+) could increase the surfaceoxygen vacancy concentration. Furthermore, it was also found that only the Cu2O-CuO heterojunctionstructure with the appropriate Cu2+/Cu+ ratio behaved the optimum catalytic activity. The kineticstudies indicated that the apparent activation energy of CO oxidation was greatly affected by the Cu2+/Cu+ ratio. Therefore, these Cu2O-CuO submicron-cubes with heterostructure were considered as thepromising CO oxidation catalysts.

Effect of the Oxygen Flux Ratio on the Structural and the Optical Properties of Silver-oxide Films Deposited by Using the Direct-current Reactive Magnetron Sputtering Method

Xiao-Yong Gao,Hong-Liang Feng,Zeng-Yuan Zhang,Jiao-Min Ma,Meng-Ke Zhao,Chao Chen,Jin-Hua Gu,Shi-E Yang,Yong-Sheng Chen,Jing-Xiao Lu 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.58 No.2

Using values of the oxygen flux ratio (OFR = [O2]/[Ar]) ranging from 0 to 0.5, authors deposited a series of silver-oxide (Ag_xO) films on glass substrates by direct-current reactive magnetron sputtering (DC sputtering) at a substrate temperature of 150 ℃. The effect of the OFR on the film’s structural and optical properties was systematically investigated by using X-ray diffractometry, scanning electron microscopy and spectrophotometry. The Ag_xO films deposited clearly show an evolution of the film’s phase structure from the biphased (Ag + Ag_2O) structure to the biphased (AgO + Ag_2O) structure and then to the single-phased (Ag_2O) structure as value of the OFR increases. Accordingly, the film’s surface morphology, related to the film’s crystalline structure, clearly changes from a loose and porous surface structure to a compact surface structure and then to a pyramid-like surface structure with increasing value of the OFR. The novel porous structure may be attributed to the interruption of the silver’s growth course by the AgO on the film’s surface. Notably, a single-phased Ag_2O film is deposited by DC-sputtering at OFR = 0.5 due to the dual effects of thermal decomposition of the AgO phase and a combination reaction of AgO and Ag to Ag_2O. The oscillations both in the film’s reflectivity and transmissivity spectra are strengthened with increasing OFR, indicating an evolution from the metallic behavior of the biphased (Ag + Ag_2O) film to the dielectric behavior of the biphased (Ag_2O + AgO) film and the single-phased Ag2O film. The fitted optical absorption edges of the Ag_2O and the Ag_xO films deposited at values of the OFR of 0.5 and 0.33 are approximately 2.43 eV and 2.34 eV, respectively. The absorption edges are closely related to the direct interband transitions.