title: Room temperature phosphorescence of metal-free organic materials in amorphous polymer matrices.
abstract: Developing metal-free organic phosphorescent materials is promising but challenging because achieving emissive triplet relaxation that outcompetes the vibrational loss of triplets, a key process to achieving phosphorescence, is difficult without heavy metal atoms. While recent studies reveal that bright room temperature phosphorescence can be realized in purely organic crystalline materials through directed halogen bonding, these organic phosphors still have limitations to practical applications due to the stringent requirement of high quality crystal formation. Here we report bright room temperature phosphorescence by embedding a purely organic phosphor into an amorphous glassy polymer matrix. Our study implies that the reduced beta (β)-relaxation of isotactic PMMA most efficiently suppresses vibrational triplet decay and allows the embedded organic phosphors to achieve a bright 7.5% phosphorescence quantum yield. We also demonstrate a microfluidic device integrated with a novel temperature sensor based on the metal-free purely organic phosphors in the temperature-sensitive polymer matrix. This unique system has many advantages: (i) simple device structures without feeding additional temperature sensing agents, (ii) bright phosphorescence emission, (iii) a reversible thermal response, and (iv) tunable temperature sensing ranges by using different polymers.
authors.affiliation: Macromolecular Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA.
authors.forename: Dongwook
authors.initials: D
authors.lastname: Lee
authors.forename: Onas
authors.initials: O
authors.lastname: Bolton
authors.forename: Byoung Choul
authors.initials: BC
authors.lastname: Kim
authors.forename: Ji Ho
authors.initials: JH
authors.lastname: Youk
authors.forename: Shuichi
authors.initials: S
authors.lastname: Takayama
authors.forename: Jinsang
authors.initials: J
authors.lastname: Kim
mesh_terms: D005456:Fluorescent Dyes; D008163:Luminescent Measurements; D009930:Organic Chemicals; D000078789:Polyacetylene Polymer; D011108:Polymers / Q000737:chemistry*; D019904:Polymethyl Methacrylate; D053279:Polyynes; D013696:Temperature
chemical_list: D005456:Fluorescent Dyes; D009930:Organic Chemicals; D000078789:Polyacetylene Polymer; D011108:Polymers; D053279:Polyynes; C082361:polydiacetylene; D019904:Polymethyl Methacrylate