Crystal Engineering of Room Temperature Phosphorescence in Organic Solids

Abstract

We report a series of highly emissive azatriangulenetrione (TANGO) solids in which the luminescent properties are controlled by engineering the molecular packing by adjusting the steric size of substituents. The co‐alignment of “phosphorogenic” carbonyl groups within the π‐stacks results in an almost pure triplet emission in HTANGO, TCTANGO, TBTANGO and TITANGO, while their rotation by ≈60° in the sterically hindered tBuTANGO leads to an almost pure singlet emission. Despite strong π‐interactions, aggregation‐induced quenching and triplet–triplet annihilation are avoided in HTANGO and TCTANGO which display efficient phosphorescence in the solid state. To our knowledge, HTANGO with the solid‐state phosphorescence quantum yield of 42 % at room temperature is the most efficient phosphor composed of the 1st/2nd raw elements only.

Heavy atom oriented orbital angular momentum manipulation in metal-free organic phosphors

“…36 For that purpose, crystal design and strong intermolecular bonding between POPs and rigid matrix have been implemented. 10,30,35,[37][38][39][40][41][42][43][44] The slow decay nature of POPs, on the other hand, has been explored to create persistent emitters with long lifetimes in the 10 À1 to 10 0 second regime. 3 However, current design strategies have reached their limit.…”

Molecular Thermal Motion Modulated Room-Temperature Phosphorescence for Multilevel Encryption

“…Purely organic room-temperature phosphorescence (RTP) materials with long lifetime have been widely applied in various areas, such as organic optoelectronics, biomedicine, optical sensing, and data encryption [1,2]. Over the past decade, strategies including halogen bonding [3,4], chargetransfer mediation [5][6][7], molecular-orbital hybridization [8,9], crystal engineering [10][11][12][13][14], polymer-matrix assistance [15][16][17][18][19][20], and host-guest doping [21][22][23][24][25][26] have been utilized to boost intersystem crossing and diminish nonradiative decays to realize organic RTP. Accordingly, ultralong RTP systems with emission wavelength even at near-infrared region can be achieved [27][28][29][30][31], which is promising in background-free bioimaging.…”

Efficient Room-Temperature Phosphorescence of Covalent Organic Frameworks through Covalent Halogen Doping

“…In recent years, organic room temperature phosphorescence (RTP) has become a 'hot' research topic, driven by both scientific curiosity (controlling spin-forbidden processes such as phosphorescence by molecular design) as well as promising practical applications. 9,10,11,12,13,14,15 The latter includes biosensing/imaging, 13 anticounterfeiting/data encryption, 16 high-efficiency organic light-emitting diodes (breaking through the unfavorable 1:3 singlet: triplet spin-statistics), 17 and photovoltaics (overcoming Shockley-Queisser limit through up-conversion), 18,19 3D displays, 20 and light-controlled triplet qubits for quantum computing applications. 21 In most cases, the design of organic RTP materials relies on i) heavy atoms or ii) functional groups that enable excitations with different orbital momenta for singlet and triplet states (eg., n-*→ -* for C=O), to increase the spin-orbit coupling and accelerate the ISC.…”