S1 Chromenopyrazole-Based Bipolar Host Materials for Solution- Processable Thermally Activated Delayed Fluorescence OLEDs Exhibiting High Efficiency and Low Roll-off Mallesham Godumala, Jiwon Yoon, Chiho Lee, Ji-Eun Jeong, Sungnam Park, Han Young Woo, Min Ju Cho and Dong Hoon Choi* Department of Chemistry, Research Institute for Natural Sciences, Korea University, 145 Anam- ro, Sungbuk-gu, Seoul 02841, Korea *Corresponding author: dhchoi8803@korea.ac.kr Table of Contents 1.0 Instrumentation, Materials, and Synthesis S2-S5 2.0 Theoretical calculations S5-S6 3.0 Thermal and morphological properties S6-S7 4.0 Photophysical properties S7-S9 5.0 Transient PL and kinetic parameters S10-S11 6.0 Electrochemical properties S11 7.0 Single carrier devices S12 8.0 Electroluminescence properties S13-S17 9.0 Device lifetime data S17 10.0 Notes and references S18-S19 Electronic Supplementary Material (ESI) for Chemical Communications. This journal is © The Royal Society of Chemistry 2019