Investigation of theoretical efficiency limit of hot carriers solar cells with a bulk indium nitride absorber

Abstract

Theoretical efficiencies of a hot carrier solar cell considering indium nitride as the absorber material have been calculated in this work. In a hot carrier solar cell highly energetic carriers are extracted from the device before thermalisation, allowing higher efficiencies in comparison to conventional solar cells. Previous reports on efficiency calculations approached the problem using two different theoretical frameworks, the particle conservation (PC) model or the impact ionization model, which are only valid in particular extreme conditions. In addition an ideal absorber material with the approximation of parabolic bands has always been considered in the past. Such assumptions give an overestimation of the efficiency limits and results can only be considered indicative. In this report the real properties of wurtzite bulk InN absorber have been taken into account for the calculation, including the actual dispersion relation and absorbance. A new hybrid model that considers particle balance and energy balance at the same time has been implemented. Effects of actual impact ionization (II) and Auger recombination (AR) lifetimes have been included in the calculations for the first time, considering the real InN band structure and thermalisation rates. It has been observed that II-AR mechanisms are useful for cell operation in particular conditions, allowing energy redistribution of hot carriers. A maximum efficiency of 43.6% has been found for 1000 suns, assuming thermalisation constants of 100 ps and ideal blackbody absorption. This value of efficiency is considerably lower than values previously calculated adopting PC or II-AR models.

Hot carrier solar cell with semi infinite energy filtering

“…1) (Wü rfel, 1997). Unfortunately, hot carrier solar cells were not successfully implemented so far, the reason being identified as too fast cooling of charge carriers in the bands of the absorber (Aliberti et al, 2010). The characteristic time of the cooling process is indeed very fast, in the picosecond range.…”

Requisites for Highly Efficient Hot-Carrier Solar Cells

“…In addition, a carrier equilibration time τ eq in the order of τ th /1,000 and an energy-selection width w esc of the ESCs narrower than 0.1 eV are needed. Aliberti et al [39,40] and Feng et al [41] have improved the present model used in Sect. 8.3 to bridge the PC model and IA model, i.e., to involve the effect of impact ionization and Auger recombination quantitatively, assuming immediate equilibration, and applied to InN absorbers.…”

“…This is exactly the reason why HC-SCs are categorized in the row "particle number conserved" in Fig. 8.1, although a slight correction for the PC model would be required depending on operating conditions [39][40][41].…”

Single layer of silicon quantum dots in silicon oxide matrix: Investigation of forming gas hydrogenation on photoluminescence properties and study of the composition of silicon rich oxide layers

“…This makes the device a very good candidate to realize energy selective contacts (ESCs), which are a crucial component of the hot carrier solar cell (HCSC). The HCSC is a promising third generation photovoltaic device for which theoretical efficiencies of 66% for non-concentrated AM 1.5 solar radiation have been predicted recently [15][16][17][18].…”