Papers by Keyword: Selective Emitter

Abstract: This paper seeks to use numerical simulation to study the effect of indium tin oxide-based emitters on the optical response and performance of nanogap thermophotovoltaic systems using a one-dimensional multi-layered model that incorporates fluctuational electrodynamics to solve the heat transfer problem. It is proposed that ITO be used as a selective emitter whose surface plasmon-polariton-enhanced heat flux spectrum is tuned by changing its processing method. In order to study the optical response of this system, an ITO layer is paired with three types of substrate materials to form three different two-layered emitters at 1000 K. It is discovered that an Ag/ITO emitter produces relatively high heat flux within a narrow spectrum as compared to the other two. It is shown that a substrate material possessing a dielectric function with low ε’ and ε” values (low absorption) contributes the least amount of heat flux and maximizes the contribution of the ITO layer at the resonant frequency producing a narrower spectral heat flux profile. Furthermore the substrate thickness has a significant effect on the heat flux spectrum especially at lower thicknesses. Finally, it is shown that by tuning ITO properties to better match the TPV cell’s band gap, higher power output and conversion efficiencies can be obtained.

Abstract: RCA cleaning in multiple variations is widely used in photovoltaic production lines for high efficiency solar cells. These commonly peroxide based cleaning procedures are effective, but suffering from large chemical consumption and waste generation. A substitution of hydrogen peroxide by ozone in cleaning solutions is not realized yet for PV devices despite its high oxidation potential and facility advantages. The very high potential of ozone cleaning has been shown in various microelectronic applications [1-7]. Dissolved ozone in HF/HCl solution gives the option of cleaning by combined silicon etching and oxidizing as well as complexing metal contaminations due to F^- and Cl^-.

Abstract: Directionally solidified (DS) oxide eutectic in situ composites are attracting increasing attention because of their unique properties and potential applications to high temperature structural materials, optical or electronic devices. Among the alumina-based eutectic composites, DS Al2O3/Er3Al5O12(EAG) eutectic is considered to be promising candidate for use as selective emitter at high temperature. In this work, eutectic in situ composites of Al2O3/EAG rods having smooth surface and full density are successfully prepared by directional solidification using the laser zone remelting method, aiming to investigate the growth characteristic of this novel binary eutectic under high temperature gradient. The microstructure is investigated by scanning electron microscopy (SEM), energy disperse spectroscopy (EDS) and X-ray diffraction (XRD). The Al2O3/EAG eutectic presents a very fine irregular network structure consisting of only -Al2O3 and Er3Al5O12 phases without grain boundaries and amorphous phases between interfaces. The eutectic interphase spacing is strongly dependent on the laser scanning rate, rapidly decreasing at the sub-micron levels for the samples grown at high rate. Furthermore, the microstructural formation and evolution of the composite are analyzed and discussed.

Abstract: In this work, we report on the last investigation of POP (selective Phosphorous doping and contact Opening Process) in crystalline silicon solar cells. For the industrial solar cells, it must be very highly doped to decrease the high-contact resistance and not very shallow so that it is not perforated during paste firing, which would short-circuit the junction. We made improvement involves making separate diffusions for the different regions since the requirements are so different: a heavily doped and thick region under the contacts, a thin and lowly doped region under the passivating layer. Furthermore we opened the metal contact area to make a narrow grid lines simultaneously. As a result we could increase fill factor and reduce contact resistance by industrial process.