Dear suhail, a healthy discussion has already discussed on RG, have a look on it:

https://www.researchgate.net/post/What_is_the_basic_difference_between_optical_band_gap_and_electrical_band_gap

https://www.researchgate.net/post/What_is_the_difference_between_optical_band_gap_and_electronic_band_gap_Where_can_I_read_about_that_Any_suggestions_for_books

Thank you dear Dear Vinay Sharma sir for adding useful information. Suhail Sayyed

Please have a look at the below links.

https://www.researchgate.net/post/What_is_the_difference_between_optical_band_gap_and_electronic_band_gap

https://www.researchgate.net/post/Is_there_any_difference_between_electrical_band_gap_and_optical_band_gap