Performance Analysis of a Near-Field Thermophotovoltaic Device With a Metallodielectric Selective Emitter and Electrical Contacts for the Photovoltaic Cell

Abstract

A near-field thermophotovoltaic (TPV) system with a multilayer emitter of alternate tungsten and alumina layer is proposed in this paper. The fluctuational electrodynamics along with the dyadic Green's function for a multilayered structure is applied to calculate the spectral heat flux, and the charge transport equations are solved to get the photocurrent generation and electrical power output. The spectral heat flux is much enhanced when plain tungsten emitter is replaced with multilayer emitter. The mechanism of surface plasmon polariton coupling in the tungsten thin film, which is responsible for the heat flux enhancement, is analyzed. In addition, the invalidity of effective medium theory to predict the optical properties of multilayer structure in near-field radiation is discussed. The tungsten and alumina layer thicknesses are optimized to match the spectral heat flux with the bandgap of TPV cell. Practically, with a gold reflector placed on the back of TPV cell, which also acts as the back electrode, and a 5-nm-thick indium tin oxide (ITO) layer as the front contact, when the emitter and receiver temperature are respectively set as 2000 K and 300 K, the conversion efficiency and electrical power output can be achieved to 23.7% and 0.31 MW/m 2 at a vacuum gap distance of 100 nm.

Tailoring near-field thermal radiation between metallo-dielectric multilayers using coupled surface plasmon polaritons

“…Although the measured heat transfer rate between MD multilayers is not the largest value among those of all homogeneous materials, the enhancement mechanism shown here can be applied to other configurations, including polar dielectric materials, to achieve even better values of heat transfer rate. Further, the tailoring of near-field thermal radiation achieved by coupled SPPs supported in metal/dielectric interfaces has been reported to make much more efficient near-field TPV systems 24 , 25 , 37 . Thus, the results obtained in this study will pave the way for real-world applications of near-field radiation transferred by MD multilayers.…”

“…To overcome these issues, focus has now shifted to controlling of near-field thermal radiation via the introduction of nanomaterials 24 , 25 , 27 – 37 . In particular, metallo-dielectric (MD) multilayers have been extensively studied because mutual interactions of surface polaritons at multiple interfaces inside multilayers 24 , 25 , 35 , 36 provide exotic features including tuning of near-field thermal radiation.…”

“…In particular, metallo-dielectric (MD) multilayers have been extensively studied because mutual interactions of surface polaritons at multiple interfaces inside multilayers 24 , 25 , 35 , 36 provide exotic features including tuning of near-field thermal radiation. Given that such tuning capability is a pivotal issue in enhancing the performance of electricity-generation systems 24 , 25 , 37 – 40 and in thermal management 41 , 42 , an experimental demonstration of the modulation of thermal radiation between MD multilayers is indispensable. Unfortunately, the control of near-field thermal radiation between MD multilayers and/or nanomaterials has not been experimentally achieved yet.…”

Transparent and ‘opaque’ conducting electrodes for ultra-thin highly-efficient near-field thermophotovoltaic cells

“…It can be seen that the usable low-loss doping range of ITO is around its loss minimum at , higher than typical TPV semiconductor bandgaps, so in most cases an ITO front electrode will be opaque at ω g . For this reason, in one previous investigation with a bulk PV cell 19 , only a 5 nm -thick 410Ω-resistance ITO electrode was shown to work without a detrimental effect to efficiency. Here, we will show that, by appropriately tuning the doping and in a thin-film-PV-cell geometry, lower- R sq ITO electrodes can also be efficiently implemented.…”

Indium antimonide photovoltaic cells for near-field thermophotovoltaics

“…Even though multiple theoretical analyses dealt with modelling the transport of electrical charges within the photovoltaic cell of a NF-TPV device [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25], the steps of (1) designing, (2) fabricating and characterizing, and (3) operating a PV cell in the near field were never completed successively. The present article is about realizing the second step in that series in the case of a cell made of indium antimonide (InSb).…”