One dimensional photonic crystal has been developed as a broadband dielectric reflector, the stopband of which could be selectively tuned based on absorption spectrum of the absorber material. The design parameters and factors which contribute to the tunability of the photonic crystals are analyzed through simulations and experiments. The photonic crystal structures are fabricated using silicon rich silicon nitride and silicon oxynitride thin films deposited by PECVD at 200 degrees C. Modulated photonic crystal with a broad bandwidth, having an integrated reflectance of 97.6% in the wavelength range 580-1200 nm has been fabricated and applied in an amorphous silicon thin film solar cell as the back reflector. The optical performance of solar cells with these back reflectors has been studied in the longer wavelength as against the conventional metallic back reflector. The characterization of the thin film silicon solar cell with these photonic structures presented a short circuit current density of 14.77 mA/cm(2). The angle dependent behaviour of the photonic crystal has been studied using angle dependent current-voltage measurement and a future prospectus of these structures as passivation layer for ultra thin crystalline silicon solar cells is also highlighted.