Silicon dominates the contemporary electronic industry. However, being an indirect band-gap material, it is a poor absorber of light, which decreases the efficiency of Si-based photodetectors and photovoltaic devices. This review highlights recent studies performed towards improving the optical absorption of Si. A summary of recent theoretical approaches based on the first principle calculation has been provided. It is followed by an overview of recent experimental approaches including scattering, plasmon, hot electron, and near-field effects. The article concludes with a perspective on the future research direction of Si-based photodetectors and photovoltaic devices.