“…Recently, polymer assemblies or aggregates and organic–inorganic heterostructures composed of polymers are used as an artificial light-harvesting antenna because of their reasonably high molar extinction coefficient and high photostability. , Fluorene-based conjugated polymers are attractive as active material in polymer light-emitting diodes (PLEDs) and photovoltaic devices. − With an alternation of poly(fluorene-2,7-diyl) (F8) and benzothiadiazole (BT) units, poly(9,9-dioctylfluorene- alt -benzothiadiazole) (F8BT) has been intensively utilized for PLED applications exhibiting high quantum and power efficiencies as a green emitter. , It is already evident that the photophysical processes of the collapsed form of polymer are significantly different from their extended form due to interchain interactions ,,, that eventually control the charge-transfer process. − In the case of polymer nanoparticles, polymeric chains are collapsed during the formation of nanoparticles in the presence of bad solvent where chromophoric units have interacted through intra- and inter-chromophoric interactions that modify the photophysical properties. ,, Favorable interchain interactions between different chromophoric subunits with different energy levels along the polymeric backbone lead to energy migration from blue absorbing subunits to low lying red subunits after excitation. , Our previous study revealed that different states with different free energy minima arise during collapsing of polymeric chains into nanoparticles which causes intra-/intrachain energy transfer and energy migration from higher energy states to the lower energy ones; this energy is funneled ultimately into a delocalized collective state which is the lowest energy sites of the collapsed form. ,,,, After photon absorption, the excited state carrier population of polymer nanoparticles relax from the vibrational hot S 1 state to relaxed S 1 state and then energy funneling occurs to low lying energy state, i.e., delocalized collective state (CL s ). These complex photophysical processes cannot be efficiently extracted using single wavelength analysis.…”