The demand for low cost solar energy technology calls for manufacturing processes using economic liquid- or gas-phase synthesis of the corresponding materials. In this regard, manufacturing of quantum dot-sensitized solar cells is particularly complicated through multiple-step preparations. Material pairs such as TiO2–PbS heterojunctions have shown high absorption of visible light and good electron transfer properties. However, traditional solution processing requires extensive surface functionalization or the use of surfactants to obtain well-defined films. Such surfactants, unfortunately, often lower electron hopping/tunneling in the system (surfactants are usually insulators) and therefore have to be removed or exchanged before completing device fabrication. Similarly, the so far presented processes to deposit PbS directly on TiO2 are very time consuming. In this paper, we present a single-step, large-scale, operable process to synthesize PbS–TiO2 heterojunction particles by aerosol synthesis using red...