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Thermally activated delayed fluorescence (TADF) systems exhibit high emissive yield due to efficient back-conversion of nonemissive triplet states to emissive singlet states via reverse intersystem crossing (RISC). In this paper, both the charge carrier and triplet exciton dynamics are explored using transient electroluminescence (TrEL) measurements in the TADF molecule, 2,3,4,6-Tetra(9H-carbazol-9-yl)-5-fluorobenzonitrile (4CzFCN)-based devices. The analysis of the rising edge of the TrEL pulse indicates that the carriers follow multiple trapping, de-trapping, and exciton recombination dynamics. The trailing edge of the TrEL pulse provides insight into the monomolecular and bimolecular exciton dynamics. These studies along with a kinetic model reveal triplet harvesting processes in a 4CzFCN molecule via both RISC and triplet–triplet annihilation (TTA). Furthermore, at high temperatures, the analysis suggests that TADF processes are dominant with negligible contribution from TTA. The presence of bimolecular triplet processes acts as bottlenecks for accessing higher efficiencies in TADF organic light emitting diodes.

Triplet state modification in organic phosphorescence molecules for a desired color and quantum yield is typically pursued by chemical modification. A facile methodology is introduced to tune the triplet state dynamics of a phosphorescent molecule by changing the host‐matrix parameters. An organic phosphor, Br2PmDI (2–Bromo pyromellitic diimide), dispersed at dilute levels (1.5 wt.%) in a semicrystalline high‐κ relaxer ferroelectric host matrix emit room‐temperature phosphorescence accompanied by a delayed fluorescence component. The host relaxer ferroelectric polymer film can be engineered to form a photonic matrix with a regular micropore structure of refractive index contrast ≈0.6 that can increase the density of optical states and introduce photonic coupling. The phosphorescence quantum yield of Br2PmDI in this photonic matrix increases by ≈2.3 fold, and the lifetime reduces by a factor of three. The coupled quantum states are investigated by time‐resolved spectroscopy at different temperatures and pump intensities.

Patterned piezoelectric polymer films serve as a suitable template for exploring various applications based on the characteristic electrical and optical properties. Here, the large‐area spontaneous pattern formation in relaxor terpolymer, poly(vinylidene difluoride‐trifluoroethylene‐chlorofluoroethelene) (P(VDF‐TrFE‐CFE)) films, is demonstrated using the cost‐effective breath‐figure technique. The experimental parameters allowed for controlling the hemispheroidal patterns, with pore dimensions varying from a few ≈100 nm to ≈ mm range. Due to the increased charge accumulation region, these porous structures exhibit enhanced ferroelectric and piezoelectric responses. Additionally, the refractive index contrast in the patterned structures leads to improved diffused reflection and thermal emittance. Furthermore, in the presence of guest‐dye molecules, the dominant amorphous phase of the patterned films results in higher photoluminescence yield. These features enable patterned films for high‐efficiency piezoelectric generators and passive daytime radiators.

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