P‐203: Effect of Substrate Temperature of n‐type Charge‐Generation Layer on the Electrical Properties of Charge‐Generation Unit

In this study, we investigated the impact of substrate temperature (T sub ) on the electrical properties of the n‐type charge generation layer (nCGL) composed of bathophenanthroline (Bphen) and Ytterbium (Yb) deposited under different T sub conditions (‐4, 20, and 40 °C). The charge generation unit fabricated at ‐4 °C exhibited superior electrical properties compared to those fabricated at 20 °C and 40 °C. To investigate the cause of this improvement, we analyzed the electron mobility and molecular orientation characteristics of nCGL. The results showed that a more well‐ordered horizontally oriented layer was formed at lower Tsub, leading to an increase in electron mobility. However, there was no significant difference in molecular orientation between the film composed only of Bphen and Bphen with Yb. The ultraviolet photoelectron spectroscopy analysis revealed that the lowest unoccupied molecular orbital energy level decreased when the Bphen was doped with Yb, indicating that an interaction occurred between the two materials. Nevertheless, this had little impact on molecular orientation. Therefore, if a host material more favorable for molecular orientation is used, the electrical properties are expected to improve more effectively.