Laser stimulated changes of the effective energy gap in chalcogenide CuInS2 photovoltaic films

The studies of changes in the energy gap of the CuInS2 photovoltaic׳s films were carried out. It was observed substantial absorption edge spectral red shift by varying laser wavelengths, power density, and beam profile. The maximum energy gap shift (up to 0.24 eV) was achieved during illumination by the Er:glass (λ=1540 nm) 35 ns pulsed lasers generating at wavelength 1.54 μm. The performed quantum chemical simulations have given an explanation of the observed photoinduced effects. The structural and quantum chemical analysis indicates on a principal role of the partial cationic atom׳s reorientations. The performed studies should open a new approach for desirable changes of photovoltaic efficiency in the studied films.