Ternary donor/acceptor system for simple single-emitting-layer white organic light emitting diodes based pure exciplexes emission

Herein, we designed pure exciplex emission, white organic light emitting diodes (WOLED) with simple single-emitting-layer (S-EML) structure through a ternary donor/acceptor system. Three kinds of donor/acceptor materials in one emitting layer of mCP:PO-T2T(1:1): x% m-MTDATA or TAPC:TPBi (1:1): x% PO-T2T could produce the white emission with high energy blue and low energy orange exciplex emission. As a result, the pure exciplex WOLED based on S-EML structure were achieved successfully with the optimized maximum luminance of 4047 cd m−2, current efficiency of 10.26 cd A−1, power efficiency of 10.57 lm W−1 and EQE of 3.4% with the two complementary color exciplex emissions. To our knowledge, this is the first time to achieve a S-EML structure pure exciplex emission WOLED. The efficient energy transfer from high energy exciplex to low energy exciplex could be also observed in this ternary system.