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The hot carrier solar cell (HCSC) concept has been proposed to overcome the Shockley Queisser limit of a single p–n junction solar cell by harvesting carriers before they have lost their surplus energy. A promising family of materials for these purposes is metal halide perovskites (MHP). MHPs have experimentally shown very long cooling times, the key requirement of a HCSC. By using ensemble Monte Carlo simulations, light is shed on why cooling times are found to be extended. This article concentrates on the role of thermalization in the cooling process. The role of carrier–phonon and carrier–carrier interactions in thermalization and cooling is specified, while showing how these processes depend on material parameters, such as the dielectric constant and effective mass. It is quantified how thermalization acts as a cooling mechanism via the cold background effect. The importance of a low degree of background doping is to achieve the observed extended cooling times. Herein, it is mapped out how perovskites should be tuned, their material parameters, carrier concentration, and purity, in order to realize a HCSC. It contributes to the debate on the cooling times in MHPs and the suitability of tin perovskites for HCSCs. [ABSTRACT FROM AUTHOR]

The hot carrier solar cell aims to significantly boost the power conversion efficiency through fully utilizing the carrier thermalization energy loss. To realize such ultraefficient solar cells, it requires that the excess energy of excited "hot" carriers is captured for power generation by reducing the rate of, or even preventing, carrier cooling. It has been known that phonon bottleneck effects (PBE) play the most decisive role in reducing the carrier thermalization rate. However, the mechanisms underlying PBE are complex and vary in different material systems and are influenced by many factors such as illumination intensity and carrier density (extrinsic), electronic band structure, and phonon dispersion (intrinsic) and quantum confinement (intrinsic). III–V semiconductors are the most popular photovoltaic materials for ultraefficient thin film solar cells due to their high crystal quality and adjustable electronic band structure. Such features reduce some of the complexity of the study of PBE and hot carrier dynamics. Therefore, it is appropriate to identify the PBE mechanisms in these III–V semiconductors. This manuscript systematically reviews the mechanisms underlying PBE in III–V semiconductors in both bulk and nanostructures. There is a tendency for an enhanced PBE in low‐dimensional III–V semiconductors due to quantum and other confinement effects. Multiple quantum wells seem the most promising material system for hot carrier solar cells. [ABSTRACT FROM AUTHOR]

Hot carrier solar cells promise theoretical power conversion efficiencies far beyond the single junction limit. However, practical implementations of hot carrier solar cells have lagged far behind those theoretical predictions. Reciprocity relations for electroluminescence from conventional single junction solar cells have been extremely helpful in driving their efficiency ever closer to the theoretical limits. In this work, we discuss how the signatures of a functioning hot carrier device should manifest experimentally when driven in reverse, that is, in electroluminescent mode. Hot carrier properties lead to deviations of the dark I–V from the Shockley diode equation that is typical for conventional single junction solar cells. These deviations are directly linked to an increase in temperature of the carriers and therefore the temperature measured from electroluminescence spectra. We also elucidate how the behaviour of hot carrier solar cells in the dark depends on whether Auger processes play a significant role, revealing a stark contrast between the regime of negligible Auger recombination (carrier conservation model) and dominant Auger recombination (impact ionisation model) for hot carrier solar cells. [ABSTRACT FROM AUTHOR]