Cs₂AgInCl₆ (CAIC) is a promising optoelectronic material due to its stability and environmental friendliness [1]. While prior work has focused on emission tuning and dopant control, ultrafast photophysics, especially parity-forbidden transitions, remain less explored [2]. Despite all the basic details of the structural, electrical, and optical spectroscopy characterisation, it is crucial to study the behaviour of charge carriers and understand the dynamics that are the root causes of optoelectronic device performance. Building on our earlier studies of self-trapped exciton (STE) emissions and photodetector applications [3], we now investigate the effects of Na/Bi co-doped CAIC NCs on charge carrier dynamics using optical pump terahertz probe spectroscopy (OPTP) and developed the UV photodetectors. The X-ray diffraction (XRD) confirmed the presence of lower impurities and a highly crystalline nature, with bandgap narrowing. UV-visible absorption, steady-state, and time-resolved Photoluminescence (PL) confirm the significantly improved absorption properties, emission intensity, and average carrier decay lifetime of Na/Bi-doped systems compared to the undoped system, which implies that lifting parity-forbidden transitions by allowing maximum transitions leads to enhanced emission intensity and a long carrier lifetime of approximately 3 µs. Despite the observation of optical spectroscopy, from OPTP measurements, the faster decay lifetime is observed with tri-exponential fits, which reveal faster decay times (τ₁, τ₂, τ₃ = 3.62, 19.26, 95.70 ps) compared to pristine CAIC (2.43, 64.24, 303.86 ps), suggesting intermediate states that promote carrier getting localised or self-trapped faster than undoped samples. Structural and optical analyses were performed to understand the system, while the Optical Pump Terahertz Probe (OPTP) revealed changes in carrier decay time, confirming altered charge carrier dynamics upon co-doping due to carrier localization [4]. All the results indicate that Na/Bi co-doping has significantly improved both the structural and optical properties after doping. However, the understanding of how carrier location affects device performance needs to be further tested, and the implications of these results on the actual performance of the devices were examined by fabricating UV detectors. The fabricated UV photodetectors followed the structure of (FTO/TiO₂/CAIC/CANIBC/CuI/Au) for undoped and Na/Bi-doped CAIC systems. Compared to the undoped systems, the device exhibits a significantly improved photocurrent on/off ratio, indicating enhanced figures of merit for a complete UV detector with Na/Bi-codoped CAIC NCs. All the results discussed in this abstract are shown in the TOC. This work highlights the importance of doping and key factors of ultrafast charge dynamics for enhancing UV photodetector performance. This investigation underscores the effective impact of Carrier dynamics with doping on ultrafast timescales for future optoelectronic applications.