Reduced Efficiency Roll-Off of Terdentate Chloroplatinum Emitter-Based Solution-Processed OLEDs through an...

Platinum complexes are highly promising emitters in the development of high-performance organic light-emitting diodes (OLEDs). However, solution-processed OLEDs of platinum complexes suffer from severe efficiency roll-off at high luminance that greatly impedes their commercial applications. To address this issue, three terdentate chloroplatinum emitters Pt1-Pt3 are designed and synthesized by using oxygen-bridged N^∧C^∧N terdentate ligands to suppress efficiency roll-off in devices. As indicated by X-ray single-crystal analysis, these emitters possess a similar square-planar configuration but exhibit different intermolecular interactions. Among them, Pt1 achieves excellent solubility (∼21 mg mL^-1), good film-forming ability, high photoluminescence quantum yield (91%), and short excited-state lifetime (2.58 μs). Solution-processed OLEDs based on Pt1 exhibit a maximum external quantum efficiency (EQE_max) of 15.02% with a small efficiency roll-off (Roll-off₁₀₀₀ = 6.72%) at the practical luminance brightness level of 1000 cd m^-2. More importantly, the large-area (100 mm²) OLEDs of Pt1 with a decent EQE_max of 6.01% and a negligible efficiency roll-off (Roll-off₁₀₀₀ = 0.99%) at 1000 cd m^-2 have been realized, representing one of the highest performances recorded to date based on terdentate platinum complexes. This work provides an effective molecular design strategy to develop terdentate platinum emitter-based highly efficient solution-processed OLEDs with small efficiency roll-off.