Chalcopyrite thin-film solar cells by industry-compatible ink-based process

• We formulate inks with metallic In and Ga nanoparticles produced by purely physical methods in an alkanethiol solvent.
• Inks can be safely coated in air and annealed in a Se atmosphere to form chalcopyrite thin-film solar cell.
• This ink-based process avoids highly toxic solvent, gas, or etches, and could be scaled-up for the industry.
• Power conversion efficiencies higher than 7% are obtained and devices are extensively characterized.

We developed a new industry-compatible ink-based process to produce efficient chalcopyrite CuIn1−xGaxSe2 thin-film solar cells. Metallic In and Ga nanoparticles were produced by purely physical methods, using a low-cost and non-explosive solvent. The solvent acts as a protection against oxidation and can be removed without leaving carbon contamination. We formulated inks that can be safely coated in air by doctor blading. The precursors were converted into a functional absorber after annealing under Se vapors in a primary vacuum. This simple two-step process led to chalcopyrite CuIn1−xGaxSe2 thin-films with strong mechanical adhesion, and power conversion efficiency higher than 7%.