Dual-Mode White Light Emissions from a Single Copolymer with an Ultralong Phosphorescence Lifetime

Abstract

Polymeric white-light-emitting materials have received extensive attention due to their excellent flexibility, easy processing, and good thermal stability. However, to develop a kind of polymer with dual-mode white light emissions, especially those accompanying ultralong afterglows, remains greatly challenging. In this work, two copolymers with different feeding ratios of carbazole-dibenzofuran, 4-bromo-1,8-naphthalimide, and N-isopropylacrylamide are designed and synthesized through photopolymerization upon ultraviolet (UV) irradiation. The obtained polymer P1 films exhibit an ultralong phosphorescence lifetime of 1.86 s with decent quantum efficiency. Notably, cold white light emissions are obtained under UV irradiation with different excitation wavelengths. After removing the irradiation source, excitation-dependent and time-dependent afterglows are engendered, including warm white afterglows with Commission Internationale de l'ećlairage (CIE) coordinates of (0.31, 0.37). Interestingly, after introducing fluorine (F) atoms into the polymer films, standard white afterglows with CIE coordinates of (0.34, 0.33) are achieved, which originate from the blue delayed fluorescence and yellow phosphorescence. The dual-mode multicolor emission properties of the polymers hold great promise for advanced anti-counterfeiting applications.

Anti-Kasha Triplet Energy Transfer: Excitation Wavelength Dependent Persistent Luminescence from Host-Guest Doping Systems

“…Ex-De luminescence is mainly attributed to the emission from different photophysical processes that requires controlled expressions of excitation dynamics. At present, it is mainly divided into three categories: emission from different excited states in single-component systems [48][49][50][51][52][53] , emission from different components in multicomponent systems [54][55][56][57][58][59] , and emission from different aggregated states in cluster systems [60][61][62][63][64][65][66][67][68][69][70][71] . The most practical strategy to achieve tunable Ex-De luminescence is utilizing multicomponent systems which have the previledge in facile preparation, conveniently tunable process and wide applicability.…”

Boosting the Phosphorescence Efficiency in Doped Organic Crystals: Critical Role of Hydrogen Bonding

“…Recently, 1,8-naphthalimide ( NI ) and its derivatives have been paid extensive attention in the field of doping phosphorescent systems. − In 2014, Taddei and co-workers reported an RTP emission with a phosphorescence lifetime of about 500 μs in a co-crystal of 1,4-diiodotetrafluorobenzene and a NI derivatives (bearing a bromine atom at the 4-position and 4-methylpyridine at the imidic N-position), and strong N–I halogen bonding interaction was cited as the main reason for the observed long-lived lifetime . In the same year, the Tian and Ma group doped NI into poly diallyldimethylammonium bromide and successfully activated the RTP of NI (τ P : 3.72 ms; ϕ P : 4.4%) .…”