Quantum dot-induced improved performance of cadmium telluride (CdTe) solar cells without a Cu buffer layer†
Abstract
Cadmium telluride (CdTe) thin-film solar cells show great potential due to their high efficiency, thermal stability, and low manufacturing cost. However, the practical performance of CdTe solar cells is often severely restricted due to the deficiency or excess of Cu diffusion, leading to a non-ohmic contact and electrical shorts and thus performance degradation. Herein, we demonstrate an innovative strategy for the fabrication of a Cu-free back contact by depositing CdTe quantum dots (QDs) on a CdTe layer using the pulsed laser deposition (PLD) technique, and find that the average relative power conversion efficiency is significantly enhanced by ∼6.2%. More importantly, the as-prepared CdTe QDs are thermally stable and CdTe with CdTe QD/Au back contact devices show no sign of degradation during exposure to air even after nearly one year. This study provides new insight into the design and property modulation of CdTe-based photovoltaics.