Yes, it does. This is a well-known phenomenon.

For particle sizes less about 100nm and less all physica, mechanical, structure and thermodynamical properties will changed including optical absorption. However the dependence will more effective for sizes less than 10nm. For more information you may read the following powerpoint

"Solid Surface and Nanoscale materials Structure" M. S. Omar Presentation · July 2016 with 156 Reads DOI: 10.13140/RG.2.2.31947.59684 Charmo, University of Charmo, University of Salahaddin, DOI:10.13140/RG.2.2.31947.59684

With decreasing the particle size the optical band gap of nanomaterials starts increasing due to quantum confinement effect, the number of overlapping of orbitals decreases with decreasing particle size and thus narrowing of width of band. Narrowing of width will results in increase of gap of C.B. and V.B..

Read the attached articles for more detailed explanation.

I agree with the colleagues above and add because the quantum confinement as the grain size decreases the energy gap increases and the materiel if indirect bandgap approaches the direct bandgap. So, your result is logically correct.

Best wishes

Thank you so much.