Using magneto-electroluminescence to analyze the influence of high temperature environment on the optoelectronic properties of OLED based on TBRb/C<sub>60</sub> structure
Abstract
<p indent="0mm">An organic light-emitting diode (OLED) based on 2,8-di-tert-butyl-5,11-bis(4-tert-butylphenyl)-6,12-diphenyltetracene (TBRb) as the hole transport and emitting layer, fullerene (C<sub>60</sub>) as the electron transport layer was fabricated, and the magneto-electroluminescence (MEL) was used to analyze the effect of high-temperature environment on the optoelectronic properties of the device. MEL exhibits a “3V” characteristic line pattern of first rising, then falling, and then rising again at <sc>300 K.</sc> It consists of four processes: intersystem crossing (ISC), reverse intersystem crossing (RISC), triplet exciton annihilation (TTA), and singlet exciton splitting (STT). The turn-on voltage of the device is only about 1V, with a half-bandgap turn-on characteristic. After the <italic>in</italic>-<italic>situ</italic> heating device reaches <sc>400 K,</sc> the MEL characteristic line shape changes to a “Y” shape. Combined with the MEL fitting, current-voltage curve, luminescence-current curve, and surface morphology of the device, we believe that structural traps are generated inside the device at <sc>400 K.</sc> These traps enhance the ISC between singlet and triplet polarons at the TBRb/C<sub>60</sub> interface, as well as the RISC process between singlet and triplet exciplex, suppressing the TTA and STT processes within the TBRb. As the temperature increases, the luminous efficiency of the device decreases, which is not conducive to luminescence. This work not only deepens the understanding of the influence of high-temperature environment on the carriers evolution process in the OLED based on TBRb/C<sub>60</sub> structure, but also provides a technical solution to monitor the structural changes of devices by using MEL.</p>
