DSC and TGA thermal properties of S1, S3 and S4

Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) measurements were carried out for S1, S3 ans S4 to obtain thermal decomposition (Td), glass transition temperatures (Tg) and melting points (Tm). For DSC Perkin Elmer DSC 6000 was used with Pyris software for data analysis, and the experiment was carried out from room temperature to 450 deg C in a N2 atmosphere at scan rate of 10 deg per minute. For TGA Perkin Elmer STA 6000 (TGA and DTA) with auto sampler was used with Pyris software for data analysis and experiment was performed from room temperature to 500 deg C in an N2 atmosphere at 10 deg per min. The compounds exhibit good thermal stability with Td (corresponding to a weight loss of 5 %) in the range of 112 to 287 C. High Tg values were observed for S1 (195 C) than for S4 (130 C). The crystallization temperature as an exothermic peak in DSC scans was not observed for S1 or S4, indicating their amorphous nature, which is required for better performance of OLEDs. The melting points exhibited in the DSC scans as sharp endothermic peaks were found to be 409 for S1 and between 227 and 244 C for S4.