Symmetry breaking charge transfer behaviour in D-A-D triad system by selective excitation.

• D-A-D triads type molecules synthesized using perylenediimde (PDI) bonded with naphthalenediimide (NDI) units via aliphatic (Triad 1) or aromatic (Triad 2) linker showed symmetry breaking charge separation (SB-CS). • SB-CS phenomenon is studied using photoluminescence, time resolved fluorescence, transient absorption spectroscopy techniques. • The organic solar cell fabricated using Triad 2 resulted in better device performance compared to Triad 1 due to increased open circuit voltage (V oc) because of more effective SB-CS state. • Triad 2 shows overall better power conversion efficiency of 4.4 % with FF 67 % in comparison to Triad 1. Multichromophoric D-A-D triads synthesized using perylenediimde (PDI) bonded with naphthalenediimide (NDI) units via aliphatic (Triad 1) or aromatic (Triad 2) linker is studied for symmetry breaking charge separation (SB-CS) by selective excitation of the NDI/PDI chromophores. NDI chromophore on excitation transfers electron to PDI chromophore and type of linker played crucial role in stability of generated CS state. Photoluminescence, time resolved fluorescense and transient absorption spectroscopy tools have been used to study the phenomenon. The optical as well as electrochemical study confirmed intramolecular electron transfer from NDI to PDI chromophore. Stable SB-CS state formation is directly resulted in increased open circuit voltage (V oc) of Triad 2 based organic solar cell devices. The selective excitation of chromophoric center and SB-CS in D-A-D type triad is the demand of present electronic device for the formation of long lived charge carrier. [ABSTRACT FROM AUTHOR]