Studies on Solution-Processed Cu2ZnSnS4 Nanoparticles

Cu2ZnSnS4 (CZTS) is identified to be a suitable candidate as an absorber layer for solar cells. In this work, CZTS nanoparticles are synthesized by wet-chemical method with non-toxic solvents and characterized for application in solar cells. The precursor concentrations are varied to achieve phase pure CZTS having a Cu-poor and Zn-rich composition, which is ideal for high-efficiency solar cells. Formation of tetragonal kesterite structured CZTS phase is confirmed from the X-ray diffraction analysis. Study also revealed the presence of shoulder peaks corresponding to Cu2S phase in Cu-rich samples. Sample with Cu/Zn+Sn ratio of 0.85 having a band gap of 1.48 eV and particle size ~ 20 nm is opted for further studies. Minority carrier lifetime of this sample is estimated to be 6 ns from time-resolved photoluminescence measurement. The work function and valence band maximum of CZTS nanoparticle system are also estimated using UPS spectrum. The study demonstrates the suitability of CZTS nanoparticle in solar cells.