S2 Table of Contents 1. Experimental procedures .....................................................................................................S3 1.1. Synthesis.......................................................................................................................S3 1.2. Thermal properties ......................................................................................................S12 1.3. Photophysical characterizations ..................................................................................S12 1.4. Fabrication and characterization of PhOLEDs............................................................S13 1.5. Photoelectron emission spectroscopy..........................................................................S13 1.6. DFT calculations .........................................................................................................S14 X-ray analysis ........................................................................................................................S15 Thermal properties .................................................................................................................S17 Figure S1. ...........................................................................................................................S17 Table S3..............................................................................................................................S17 Table S4..............................................................................................................................S17 Temperature dependent PL measurements in doped polymer films......................................S18 Figure S2. ...........................................................................................................................S19 Figure S3. ...........................................................................................................................S20 Photophysical properties ........................................................................................................S20 Table S5..............................................................................................................................S20 Figure S4. ...........................................................................................................................S21 Table S6..............................................................................................................................S21 DFT Calculations ...................................................................................................................S22 Table S7..............................................................................................................................S22 Figure S5. ...........................................................................................................................S23 Table S8..............................................................................................................................S23 Electrical and electroluminescent properties .........................................................................S24 Figure S6. ...........................................................................................................................S24 Figure S7. ...........................................................................................................................S24 Figure S8. ...........................................................................................................................S25 Figure S9. ...........................................................................................................................S25 Figure S10. .........................................................................................................................S26 Figure S11. .........................................................................................................................S26 Table S9..............................................................................................................................S27 DFT optimized molecular geometries ...................................................................................S28 References..............................................................................................................................S34