In rapidly increasing global-energy demand, solar energy is the cleanest and sustainable energy source. The most efficient way to harvest the solar energy is to convert it directly into electricity using solar cells. In recent years, metal-halide-perovskite photovoltaics (PerPV) emerged as a promising and cost-effective alternative to other technologies due to roll-to-roll processing and easy installation. The solution processed organic-inorganic hybrid perovskite films exhibit unprecedented photo-physical properties compared to the inorganic semiconductors like GaAs etc. In these semiconductors, the nano-morphology and its structure-property correlation determines the fundamental nature of photon to free charge generation processes. The optimal device architecture is detrimental in mitigating the charge carrier recombination losses and to enhance the device efficiency. Ultrafast Transient Absorption Spectroscopy (TAS) technique having 20 % in these systems. The interplay between the miscibility and nucleation of perovskite structure is utilised to self-assemble hierarchical bandgap of 2D/3D hybrid perovskites as a photodetector active layer, which exhibits wavelength dependent photocurrent characteristics. We demonstrated single-pixel color-sensor based on this graded bandgap perovskite structure. In a symmetric hole-only device, the photocurrent features across the UV-Vis spectrum obtained photocurrent signals without dispersive optical elements. Finally, I will present the nature of drift of ionic defects mapped using photoluminescence microscopy in the lateral device geometry.