Revival of solar paint concept: air-processable solar Paints for the fabrication of quantum dot-sensitized solar cells

One way to revolutionize solar energy production and expand it to a large scale is to reduce the manufacturing cost and complexity of the fabrication process. The ability to make solar cells on the surface of any shape would further transform this technology. Quantum dot-sensitized solar cells (QDSSCs) are an ideal candidate to push solar cell technology in this direction. In this regard, making a paint that can be applied by a paint brush to any transparent conductive surface to turn it into the photoanode of QDSSCs is the ultimate goal. We herein demonstrate the feasibility of one-coat fabrication of QDSSCs from a lead sulfide (PbS)-based solar paint. This is possible because of its unique ability to regenerate after oxidation occurred during heat treatment in air. Hence, the whole fabrication process can be carried out in air unlike a first-generation solar paint based on cadmium sulfide (CdS) and cadmium selenide (CdSe). Two solar paints using a commercially available titanium dioxide (TiO2) and a p-type TiO2 powder were synthesized and evaluated. Also, the performance-limiting parameters are thoroughly investigated using various spectroscopic and electrochemical characterization methods. The implication of new insights into the PbS-based solar paint for further development of paint-on solar cells is discussed.