Thermal-Carrier-Escape Mitigation in a Quantum-Dot-In-Perovskite Intermediate Band Solar Cell via Bandgap Engineering

TL;DR

This paper demonstrates that quantum-dot-in-perovskite solar cells can effectively mitigate thermal escape of carriers from the intermediate band through bandgap engineering, enabling high-efficiency intermediate band solar cells at room temperature.

Contribution

It introduces a method to suppress thermal carrier escape in IBSCs by bandgap engineering in QDiP materials, advancing the development of high-efficiency solar cells.

Findings

The IB is thermally decoupled from VB and CB in QDiP solids.

The activation energy for thermal escape is measured at 204 meV.

Thermal escape mitigation is effective at room temperature.

Abstract

By harvesting a wider range of the solar spectrum, intermediate band solar cells (IBSCs) can achieve efficiencies 50% higher than conventional single-junction solar cells. For this, additional requirements are imposed to the light-absorbing semiconductor, which must contain a collection of in-gap levels, called intermediate band (IB), optically coupled to but thermally decoupled from the valence and conduction bands (VB and CB). Quantum-dot-in-perovskite (QDiP) solids, where inorganic quantum dots (QDs) are embedded in a halide perovskite matrix, have been recently suggested as a promising material platform for developing IBSCs. In this work, QDiP solids with excellent morphological and structural quality and strong absorption and emission related to the presence of in-gap QD levels are synthesized. With them, QDiP-based IBSCs are fabricated and, by means of temperature-dependent photocurrent measurements, it is shown that the IB is strongly thermally decoupled from the valence and conduction bands. The activation energy of the IB$\rightarrow$CB thermal escape of electrons is measured to be 204 meV, resulting in the mitigation of this detrimental process even under room-temperature operation, thus fulfilling the first mandatory requisite to enable high-efficiency IBSCs.