High charge-carrier mobilities in blends of poly(triarylamine) and TIPS- pentacene leading to better performing X-ray sensors

A new class of X-ray sensor – in which there is a blend of poly(triarylamine) (PTAA) and 6,13-bis(triisopropylsilylethynyl) (TIPS)-pentacene in the active layer of a diode structure – has been developed. The crystalline pentacene provides a fast route for charge carriers and leads to enhanced performance of the sensor. The first time-of-flight charge-carrier mobility measurement of this blend is reported. The mobility of PTAA and TIPS-pentacene in a 1:25 molar ratio was found to be 2.2×10 -5 cm 2 V -1 s -1 (averaged for field strengths between 3×10 4 and 4×10 5 Vcm -1 ), which is about 17 times higher than that obtained in PTAA over the same range of field strengths. This higher mobility is correlated with a four-fold increase in the Xray detection sensitivity in the PTAA:TIPS-pentacene devices.