Solution-processed Cd-substituted CZTS nanocrystals for sensitized liquid junction solar cells

•Synthesis of Cu2CdSnS4 (CCTS) and Cu2ZnSnS4 (CZTS) nanocrystals using low-cost homemade hot-injection method.•First-principles DFT calculated phonon dispersion shows that both CCTS and CZTS are stable at ambient pressure.•Bandgap reduction from 1.51 eV (kesterite- CZTS) to 1.1 eV (stannite-CCTS) is demonstrated.•Fabricated CCTS nanocrystals sensitize solar cell exhibits a power conversion efficiency of 1.1% compared to 0.25% for CZTS.