Fig. 1

Design of pentacene dimers and their optical properties. a Chemical structures of 2P-PDPP, 2P-TDPP and 2P-SeDPP. b Steady-state absorption spectra of the three molecules; and c their transient absorption spectra (TA) collected at 1 ps pump-probe delay. All three molecules were dissolved in chlorobenzene at 25 μM concentration for the TA measurements, and excited using 0.1 mW pump pulses. For 2P-PDPP the excitation wavelength was 670 nm while it was 650 nm for both 2P-TDPP (red) and 2P-SeDPP (blue). Inset: Transient absorption kinetics taken at the photoinduced absorption peak at 504 nm