A new strategy for structuring white organic light-emitting diodes by combining complementary emissions in the same interface†
In this work, we proposed a new strategy for structuring white organic light-emitting diodes (WOLEDs) using all exciplex emissions, where the white devices can be fabricated by simply depositing several exciplex acceptor layers on the same exciplex donor layer in a vertical direction, and complementary exciplex emissions can be realized in the same exciplex donor layer interface for forming white emission. Based on this new strategy, a series of WOLEDs with different array arrangements of different exciplex acceptor layers on the same exciplex donor layer were demonstrated. The device with a bisected blue-yellow exciplex acceptor layer on the same exciplex donor layer realizes good two-color white emission with a high color rendering index of 71, and also achieves a high current efficiency of 3.17 cd A−1. Moreover, the emission spectra and device performance of white devices can be adjusted and improved by simply changing the array arrangements of different exciplex acceptor layers on the same exciplex donor layer. More importantly, the proposed new strategy can effectively solve the interface problem induced by employing interface exciplexes to realize multi-color white emission, which provides a new approach to accomplish all exciplex emission WOLEDs.