We demonstrate novel approaches to harness entire solar spectrum via nano-templates with lanthanide-based upconversion and downshifting materials. The nano-template is prepared using nanoimprint technique that lends itself to large area fabrication of nano-patterns, and it enhances the efficiency of spectrum conversion process through the excitation of resonant modes near the band edge of the materials. For practical applicability of this template, organic solar cells with the lanthanide based nano-template are evaluated showing distinctively improved efficiency, and double imprinting technique are devised to generate color tunability. The material-agnostic nano-patterning methodology is further extended to a sol-gel-based CuInGaS₂ (CIGS) solution to improve simultaneously optical and electrical performance in thin film solar cells.