It is obvious that there is the relation between crystal size, strains and band gap. The correlation between the structural and optical properties with the precursor molarity suggests that the crystallite size of the films is predominantly influenced by the band gap energy and the precursor molarity. The structural lattice parameters decrease with increasing crystallite size. However, lattice strain increases with increasing crystallite-size. Further, since the crystallite size and grain size depend on nucleation and growth kinetics during processing, they may be different for different materials because the temperature sensitivity and melting points are also different for different materials. However, Further, since the crystallite size and grain size depend on nucleation and growth kinetics during processing, they may be different for different materials because the temperature sensitivity and melting points are also different for different materials.