Effective Energy Transfer for Green, Orange, and Red Phosphorescent Organic Light‐Emitting Diodes Based on a Bipolar Deep‐Blue Emitter with Low Efficiency Roll‐Off at High Brightne... oleh Guo-Xi Yang, Jie-Ji Zhu, Shan-Shun Tang, Hong-Ji Tan, Xin He, Jing-Xin Jian, Xu-Hui Zheng, Qing-Xiao Tong