Micro-Concentrated Photovoltaics Based on Cu(In,Ga)Se2 Microcells: An Optical Study

Micro-concentrated Cu(In,Ga)Se2 (μCPV-CIGSe) solar cells offer the potential to reduce the consumption of raw materials to a great extent while maintaining high efficiencies. A theoretical model of μCPV-CIGSe solar cells, consisting of hexagonally spaced micro-CIGSe solar cells embedded in the low-index dielectric matrix and micro-sized lenses placed right on top, is proposed for optical study. It is discovered that micro-lenses enable to effectively concentrate the incident light due to the inherent nanojet phenomenon, and the μ-CIGSe absorbers trap the penetrated light within absorbers arising from wave-guided modes. The two effects co-contribute to an optimized absorption for μCPV-CIGSe solar cells with a μ-CIGSe absorber diameter of 800 nm and a pitch of 1500 nm. Short-circuit current density reaches 36.5 mA/cm2 and accounts for 98.8% compared to their plain counterparts without lenses, corresponding to an absorber material saving by a factor of 3/4. Notably, a large contacting area between lenses and CIGSe solar cells are recommended for an improved angular tolerance. Those findings will recommend design principles for further experiments.

Band Gap of Pb(Fe0.5Nb0.5)O3 Thin Films Prepared by Pulsed Laser Deposition

Ferroelectric materials have gained high interest for photovoltaic applications due to their open-circuit voltage not being limited to the band gap of the material. In the past, different lead‑based ferroelectric perovskite thin films such as Pb(Zr,Ti)O3 (Pb,La)(Zr,Ti)O3 and PbTiO3 were investigated with respect to their photovoltaic efficiency. Nevertheless, due to their high band gaps they only absorb photons in the UV spectral range. The well-known ferroelectric PbFe0.5Nb0.5O3 (PFN), which is in a structure similar to the other three, has not been considered as a possible candidate until now. We found that the band gap of PFN is around 2.75 eV and that the conductivity can be increased from 23 S/µm to 35 S/µm during illumination. The relatively low band gap value makes PFN a promising candidate as an absorber material.

SYNTHESIS POLYMER MATRIX COMPOSITE EPOXY FeNdB-Cu FOR RADAR ABSORBER COATING APPLICATION

SYNTHESIS POLYMER MATRIX COMPOSITE EPOXY FeNdB-Cu FOR RADAR ABSORBER COATING APPLICATION. Radar (Radio Detection and Ranging) is a technology using the principle of electromagnetic for detecting, measuring, and mapping target coordinates. So stealth technology was created to tackle these threats, one of which is the radar absorber coating method (RAC). This research aims to identify the effect addition of Cu to Fe-Nd-B radar absorber material as polymer matrix composite (PMC). The processes were done by powder metallurgy method, started by milling and mechanical alloying process using planetary ball mill for 60 minutes 1000 rpm, 25 kg/mm2 of compaction load, and sintering at the temperature 1000 oC for 3 hours. The coating process was carried out conventional method as much as 1 layer, the variation of resin and magnetic powder are (95:5), (90:10), and (85:5) with the addition of Cu 1%wt. Based on the characterization the lowest RL was obtained at the composition (85:15) with the value 32.08 dB at the frequency of 10.36 GHz, magnetic characterization after doping addition coercivity 0.096 kOe and Saturation 5.22 kG. PMC hardness was raising following to addition of magnetic powder with the 29.2 HD Shore D, and adhesivity value was decreased following to addition of magnetic powder to 0.5 MPa.

Investigation of Initial Transmission Effect on Saturable Absorber Optical Performance of Passive Q-Switching Doped Fiber Laser

Study of initial transmission effect on performance of saturable absorber material with Er+3 doped fiber laser was studied. Cr+4: YAG used as a saturable absorber (SA) in the study. Software computer program buildup in this study for numerical solving of rate equations model by Rung - Kutta –Fehlberg method. The study reported that the maximum optical bleaching, Threshold population inversion density are occurs at earlier buildup time of passive Q-switched, and the pulse reaches high power whenever SA characterized by low initial transmission. The study explains that related to the effect of SA initial transmission on the number density of photons feedback in resonator of laser system.