Visible to Near-Infrared Broadband Photodetector Employing Thin Film Topological Insulator Heterojunction (P-Tlbise2/N-Si) Diode

•The p-TlBiSe2 is an exotic topological insulator with less defect and disordered state, has considerable band gap and potential in spintronics and photo electric devices.•The p-TlBiSe2/n-Si heterojunction will synergize the transport property and will open a new dimension for the Si based optical industries.•Our manuscript contains very significant work in the area of heterojunction device fabrications with topological insulators and Si. We realized the heterostructure of quasi-2D-topological insulators films and n-Si for the formation of the p-n diode.•The good rectification ratio (RR ∼ 718 at ± 3 V) and figure of merit (FOM) in p-TlBiSe2/n-Si heterojunction for switching and other electronics applications.•The ultrafast measurements of p-TlBiSe2/n-Si heterojunction showed optical excitation in TlBiSe2 with a strong modification of exciton transitions in Si.•Evidence of efficient charge separation in photoexcited p-TlBiSe2/n-Si heterojunction due to the presence of the charge state (CT).•The p-TlBiSe2/n-Si heterojunction has shown good responsivity and broadband photo detectivity from visible to near-infrared region in dual quadrants.•The 2-diode simulation is used to study the devices for various detrimental mechanisms such as recombination by studying the Current density- Voltage (J-V) and ideality factor-Voltage (n-V) curve. The study gives important insight into the optimization of devices for solar cells.