Solution Processed Infrared- and Thermo- Photovoltaics based on 0.7 eV Bandgap PbS Colloidal Quantum Dots

TL;DR

This paper presents solution-processed PbS colloidal quantum dot photovoltaic devices with a 0.7 eV bandgap, enabling efficient infrared photon harvesting for solar and thermo-photovoltaic applications, with record high current and efficiency metrics.

Contribution

It introduces a novel low-cost, solution-processed PbS CQD solar cell technology with a 0.7 eV bandgap for infrared energy harvesting, expanding beyond traditional high-cost semiconductor materials.

Findings

Achieved a record high short circuit current of 37 mA/cm2 under full solar spectrum.

Demonstrated 6.4% power conversion efficiency in solar applications.

Reached ~6% efficiency as a thermo-photovoltaic cell under 1000°C blackbody radiation.

Abstract

Harnessing low energy photons is of paramount importance for multi-junction high efficiency solar cells as well as for thermo-photovoltaic applications. However, semiconductor absorbers with bandgap lower than 0.8 eV have been limited to III-V (InGaAs) or IV (Ge) semiconductors that are characterized by high manufacturing costs and complicated lattice matching requirements in their growth and integration with the higher bandgap cells. Here, we have developed solution processed low bandgap photovoltaic devices based on PbS colloidal quantum dots (CQDs) with a bandgap of 0.7 eV suited for both thermo-photovoltaic as well as low energy solar photon harvesting. By matching the spectral response of those cells to that of the infrared solar spectrum, we report a record high short circuit current (JSC) of 37 mA/cm2 under full solar spectrum and 5.5 mA/cm2 when placed at the back of a silicon wafer resulting in power conversion efficiencies (PCE) of 6.4 % and 0.7 % respectively. Moreover, the device reached an above bandgap PCE of ~6 % as a thermo-photovoltaic cell recorded under a 1000 {\deg}C blackbody radiator.