An ink for forming CIGS photovoltaic
cell active
layers is disclosed along with methods for making the ink, methods for making the active
layers and a
solar cell made with the
active layer. The ink contains a mixture of nanoparticles of elements of groups IB, IIIA and (optionally) VIA. The particles are in a desired particle size range of between about 1 nm and about 500 nm in
diameter, where a majority of the
mass of the particles comprises particles
ranging in size from no more than about 40% above or below an average particle size or, if the average particle size is less than about 5 nanometers, from no more than about 2 nanometers above or below the average particle size. The use of such ink avoids the need to
expose the material to an H2Se gas during the construction of a photovoltaic
cell and allows more uniform melting during film annealing, more uniform intermixing of nanoparticles, and allows higher quality absorber films to be formed.