Investigation of contact grid geometry for photon-enhanced thermionic emission (PETE) silicon based solar converters

Abstract

Conversion of solar radiation to electricity with photon-enhanced thermionic emission (PETE) holds the theoretical promise of high conversion efficiency. Basic questions of converter materials properties and conversion process thermodynamics were addressed in recent work. Here we investigate two configurations of front and back electrical contacts on a silicon cathode, and the dependence of device efficiency on the contact area, using a two-dimensional detailed simulation. The impact of contact area on efficiency is different at moderate vs. high temperature, due to a change from electron recombination to electron injection at the contact. When the contact is small enough, a local potential gradient develops, which forms an effective barrier against electron recombination. The back contacts lead to higher efficiency compared to front contacts at all temperatures, and allow much higher contact area that may serve to reduce Ohmic loss and to absorb IR radiation.

Solar energy conversion with photon-enhanced thermionic emission

“…The contact geometry for PETE Si cathodes was investigated for both front and back contacts, using a detailed 2D model [24]. Figure 9(b) shows that for moderate cathode temperatures, a smaller contact grid area is preferable.…”

“…The more general model with equations ( 9)-( 11) has been solved for cases where the simplified diffusion equation treatment is insufficient, including a one-dimensional slab geometry with internal junctions [18] and for two-dimensional geometry [24]. It should be noted that in both modeling approaches described above, there is no treatment of photon recycling: photons that are emitted internally due to radiative recombination are considered as lost, even though some of them are reabsorbed in the cathode and generate new electron-hole pairs.…”

Study on AlxGa1-xAs nanocones with variable Al composition structures for highly efficient light trapping

“…Since the introduction of PETE technology, how to develop high-efficiency photocathode has been a key challenge. Since then, people have dedicated themselves to improving the performance of the device, and have proposed various models and structures (Westover et al 2010;Segev et al 2015;Sandovsky et al 2016). Al x Ga 1-x As/GaAs has a variable band gap structure and has been widely used in photocathode and solar energy collection converters.…”