Fine Tuning of Hydrogen Bonding Interaction on Boosting the Room-Temperature Phosphorescence in Organic Host–Guest System

Organic room-temperature phosphorescence (RTP) materials
have demonstrated
great potential applications in optoelectronics, anticounterfeiting,
and biomedicine fields. Among them, the RTP properties of host–guest
systems can be easily regulated by changing their component parameters,
which has attracted widespread attention. However, the key factor
of the hosts (crystalline or noncovalent interaction network) for
boosting phosphorescence emission at room temperature was still unclear.
Herein, a triphenyl phosphor in the estradiol system was heated to
remove the crystal water and then cooled to turn it into a powder.
This enabled the afterglow brightness to improve by more than 90-fold
and the phosphorescent quantum yield by over 700-fold. Further studies
have indicated that the hydrogen bonding interactions of estradiol’s
−OH group were tuned during these processes, from bonding with
crystal water to bonding with guests and then constructing a strong
network with the guests. The triplet excitons thus were effectively
stabilized, which, coupled with the suitable T1 energy
level of the host, could significantly enhance the phosphorescence
in the amorphous estradiol system. This work demonstrates fine-tuning
of the hydrogen bonding interactions inside the doped estradiol RTP
system to boost its phosphorescence. It also substantiates that a
noncovalent interaction network is more important than crystalline
for efficient phosphorescence in a host–guest RTP system.