Semiconductor quantum dots have extremely small size and high absorption cross section. This makes it possible for a thin layer of them to capture nearly all of the incident solar light in the visible region. As a result, they are of great interest for solar cells. Current techniques for the deposition and annealing of semiconductor films are time-intensive, requiring multiple steps and one or two days to attain the best performing cells.

Prashant Kamat and colleagues, University of Notre Dame, Indiana, USA, have developed a simple paint-like techique for creating quantum dot solar cells. They use a binder-free paste consisting of CdS, CdSe, and TiO₂ semiconductor nanoparticles. A single coat of this paste was applied to solar cell electrodes in less than an hour by using a conventional paint brush approach under ambient conditions. Power conversion efficiencies of over 1 % were obtained, representing a promising first step for the preparation of large area and economically viable solar cells.

• Sun-Believable Solar Paint. A Transformative One-Step Approach for Designing Nanocrystalline Solar Cells
  M. P. Genovese, I. V. Lightcap, P. V. Kamat,
  ACS Nano 2011.
  DOI: 10.1021/nn204381g