Facile microwave-assisted synthesis of multiphase CuInSe2 nanoparticles and the role of secondary CuSe phase on photovoltaic device performance

Multiphase CuInSe₂ (CISe) nanoparticles including the secondary CuSe phase are synthesized by a polyol-based, microwave-assisted solvothermal method. The critical role of CuSe phase in generating the pore-free, dense CISe absorber layer for a high performance thin-film photovoltaic device is investigated through the comparative study on CISe absorber layers derived from both multiphase and single phase CISe nanoparticles. The high performance, solution-processed CISe thin-film solar cell, with a conversion efficiency of 8.2%, is obtained based on multiphase CISe nanoparticles that undergo the dramatic microstructural evolution, phase transformation, and composition adjustment during annealing under Se atmosphere.