Ternary Composites with PbS Quantum Dots for Hybrid Photovoltaics

Ternary hybrid photovoltaics based on polymers, fullerenes, and colloidal semiconductor quantum dots (QDs) bring together high efficiency and technological flexibility. To increase the performance of such hybrid solar cells, a thorough control over both film morphology and charge transport is required. In the present work, the morphology and optical properties of films of binary and ternary blends of PbS QDs with poly(3-hexylthiophene-2,5diyl) and [6,6]-phenyl C₇₁ butyric acid methyl ester have been investigated by steady-state and time-resolved photoluminescence spectroscopy, atomic force microscopy, and confocal laser-scanning microscopy. The influence of postdeposition and liquid-phase ligand exchange procedures on film properties has been considered. It is shown that the liquid-phase iodide passivation improves both film quality and charge-transfer efficiency. The mixture of three components facilitates charge transfer in the hybrid material, but a thorough control over QD size and ligand type is required.