PbS/ZnO Heterojunction Colloidal Quantum Dot Photovoltaic Devices by a Room Temperature Air-Spray Method

Colloidal quantum-dot-based photovoltaic devices (CQDPVs) were fabricated at room temperature in air atmosphere via a spraying technique. Lead sulfide colloidal quantum dots (CQDs) were utilized for this process and various fabrication conditions such as the spraying pressure, types of ligand molecules, duration of ligand exchange, and the band-gap of the CQDs were investigated in order to optimize the device performance. The power conversion efficiency reached 4.00% (
$V_{{\rm OC}}$
of 0.57 V,
$J_{{\rm SC}}$
of 11.79 mA·cm
⁻²
, and FF of 0.60) when ∼145 nm thick sprayed CQD layers were utilized; this value is comparable to that achieved with the conventional spin-coated devices. The generality of the conditions used for fabrication of the sprayed CQDPVs was demonstrated in the fabrication of various CQDs having different band-gaps (1.34–1.61 eV). This technique provides an avenue for the application of a high-throughput process for CQDPV fabrication. Because the materials used herein for device fabrication are not completely optimized, there is further scope for improving device performance.