Organic Halides and Nanocone Plastic Structures Enhance the Energy Conversion Efficiency and Self-Cleaning Ability of Colloidal Quantum Dot Photovoltaic Devices

This paper presents solid-state ligand exchange of spin-coated colloidal lead sulfide quantum dot (PbS QD) films by methylammonium iodide (MAI) and integration of them in depleted heterojunction solar (DHS) devices having an antireflecting (AR) nanocone plastic structure. Time-resolved photoluminescence measurements determine a shorter lifetime of the charge carries on a semiconductor (TiO2) electron transfer layer for the MAI-passivated QD films as compared with those with long-chain aliphatic or short thiol ligands. Consequently, the DHS device yields improved power conversion efficiency (>125%) relative to oleic-acid-passivated PbS QD films. Using anodized aluminum oxide templates, an inverted nanocone polydimethylsiloxane structure was also prepared and utilized as an AR layer in the DHS device. The solar cells exhibit an energy conversion efficiency of 7.5% with enhanced water-repellant ability.