Constructing Donor-Resonance-Donor Molecules for Acceptor-Free Bipolar Organic Semiconductors
Resonance variability and photophysical properties of the D-r-D molecules. (a) Correlation between bond and resonance variations of N-P = X (X = O, S, or Se). B.O. refers to bond order. (b) Theoretical activation energy of resonance variation () between N-P = X and N+ = P-X- resonance isomers. (c, d) UV-absorption (solid symbols) and photoluminescence (PL) spectra (open symbols) of t-BuPO, t-BuPS, and t-BuPSe in (c) CH2Cl2 solution (~10-5 mol L-1) and (d) solid films.