TY - JOUR
T1 - The effects of extended conjugation length of purely organic phosphors on their phosphorescence emission properties
AU - Hashemi, Daniel
N1 - We synthesized a series of purely organic phosphors, bromobenzaldehyde derivatives, with varying conjugation length to investigate the effects of conjugation length on their phosphorescence emission properties. As the conjugation length increases phosphorescence efficiency decreases with a redshift in the em
PY - 2015/6/16
Y1 - 2015/6/16
N2 - We synthesized a series of purely organic phosphors, bromobenzaldehyde derivatives, with varying conjugation length to investigate the effects of conjugation length on their phosphorescence emission properties. As the conjugation length increases phosphorescence efficiency decreases with a redshift in the emission color at 77 K. Our computational results imply that this correlation is related to the intersystem crossing rate and that the rate is determined by spin–orbit coupling strength rather than by simply the energy difference between the lowest lying singlet and triplet states. TD-DFT calculations show that the S 1 → T 1 transition occurs more dominantly than the S 1 → T 2 transition for all cases. Moreover, singlet excited states are localized on the aldehyde functional group, regardless of the conjugation length, while triplet excited states are evenly distributed over the conjugated backbone. Consequently, as the conjugation length increases, the larger spatial separation between singlet and triplet states diminishes the spin–orbit coupling efficiency, resulting in reduced phosphorescence.
AB - We synthesized a series of purely organic phosphors, bromobenzaldehyde derivatives, with varying conjugation length to investigate the effects of conjugation length on their phosphorescence emission properties. As the conjugation length increases phosphorescence efficiency decreases with a redshift in the emission color at 77 K. Our computational results imply that this correlation is related to the intersystem crossing rate and that the rate is determined by spin–orbit coupling strength rather than by simply the energy difference between the lowest lying singlet and triplet states. TD-DFT calculations show that the S 1 → T 1 transition occurs more dominantly than the S 1 → T 2 transition for all cases. Moreover, singlet excited states are localized on the aldehyde functional group, regardless of the conjugation length, while triplet excited states are evenly distributed over the conjugated backbone. Consequently, as the conjugation length increases, the larger spatial separation between singlet and triplet states diminishes the spin–orbit coupling efficiency, resulting in reduced phosphorescence.
UR - https://pubs.rsc.org/en/content/articlelanding/2015/cp/c5cp01003a/unauth
M3 - Article
JO - Phys. Chem. Chem. Phys.
JF - Phys. Chem. Chem. Phys.
ER -