Nanowerk  November 25, 2021 A promising way to realize photon upconversion (PUC) is through triplet-triplet annihilation (TTA). Researchers in Japan discovered that ANNP, a hydrocarbon molecule originally developed for blue organic LEDs, was an excellent annihilator. They mixed it with platinum octaethylporphyrin (PtOEP), a staple sensitizer that absorbs green light. They demonstrated substantial advantages of the van der Waals solid solution concept to yield molecular crystals with extraordinary performance. A 0.001%-order porphyrin sensitizer is dissolved during recrystallization into the molecular crystals of a blue-fluorescent hydrocarbon annihilator, 9-(2-naphthyl)-10-[4-(1-naphthyl)phenyl]anthracene (ANNP). The solid crystals they produced were highly stable and exhibited outstanding performance. […]