Recently, there has been intense interest in pure organic room‐temperature phosphorescence (ORTP) from cocrystals composed of 1,4‐diiodotetrafluorobenzene (DITFB) and a variety of polycyclic aromatic hydrocarbons (PAHs) or their derivatives. To expand the possibility of halogen bonding‐based cocrystals, the relationship between the crystal packing motifs and ORTP characteristics in binary cocrystals composed of DITFB and PAHs of phenanthrene (Phen), chrysene (Chry), and pyrene (Pyr), respectively, is investigated. The σ‐hole···π and π‐hole···π interactions determine not only the crystal packing motifs but also photoluminescence quantum yields (PLQYs). The Phen‐DITFB and Chry‐DITFB binary cocrystals with σ‐hole···π interactions show higher PLQY compared with the Pyr‐DITFB binary cocrystal with π‐hole···π interaction. Further, to clarify the effect of crystal structures on PLQY, ternary cocrystals are prepared by partially doping Pyr into Phen‐DITFB. The crystal packing motif of the ternary cocrystal originates from a Phen‐DITFB cocrystal with σ‐hole···π interaction, and some of the Phen sites are randomly replaced with Pyr molecules. The ORTP emission is derived from Pyr. The maximum PLQY is >20% due to suppressing nonradiative decay by changing the crystal packing motif.

The limitation of lasing duration less than nanosecond order has been a major problem for realizing organic solid-state continues-wave (CW) lasers and organic semiconductor laser diodes. Triplets accumulation under CW excitation has been well recognized as a critical inhibiting factor. To overcome this issue, the utilization of thermally activated delayed fluorescence (TADF) emitters is a promising mechanism because of efficient reverse intersystem crossing. Herein, we model the triplet accumulation processes under lasing and propose the active utilization of TADF for lasing based on our simulation analysis. We used the rate constants experimentally determined from the optical properties of a boron difluoride curcuminoid fluorophore showing both TADF and lasing. We demonstrate that the intersystem crossing efficiency is gradually increased after the convergence of relaxation oscillation, i.e., terminating laser oscillation. In addition, we found that when the reverse intersystem crossing rate is close to the intersystem crossing rate, CW lasing becomes dominant.

Noninvasive treatment of pressure ulcers with undermining is often difficult. To decrease the risk of bleeding in such conditions, negative pressure wound therapy (NPWT) has been applied. We treated a pressure ulcer with wide undermining using NPWT after opening drainage holes in the undermined area. This method can reduce the risk of bleeding and promote the rapid closure of the undermined area.

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