A deep-blue thermally activated delayed fluorescence (TADF) emitter TXADO-spiro-DMACF has been reported for nondoped organic light-emitting diodes (OLEDs) by integrating an appropriate blocking unit with the donor (D)-acceptor (A)-donor (D)-type TADF emitter via a spiro linkage. Benefiting from the characteristic perpendicular arrangement, the intermolecular interactions are expected to be weakened to some degree. As a result, TXADO-spiro-DMACF shows a very small bathochromic shift of 8 nm associated with a narrowed full width at half maximum of 54 nm on going from solution to the film. The corresponding nondoped device successfully achieves a bright deep-blue emission, revealing Commission Internationale de l'Eclairage coordinates of (0.16, 0.09) and a peak external quantum efficiency of 5.3% (5.3 cd/A, 5.9 lm/W). The results clearly indicate that spiro-blocking is a promising strategy to develop deep-blue TADF emitters capable of nondoped OLEDs.

Blocking (statistics)

10.1021/acsomega.8b03296

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Citations (44)

An arylphosphine oxide and phosphonate combination as a solution processable electron injection layer for power-efficient PLEDs

Journal of Materials Chemistry C (2019)

Xuefei Li Keyan Bai Shumeng Wang Junqiao Ding Lixiang Wang

An all organic mixed electron injection layer composed of SPPO13:TPPO has been newly developed to construct fully solution-processed PLEDs with high power efficiency.

Phosphonate

10.1039/c8tc05961f

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Citations (5)

Dynamic Crosswalk Signal Timing Optimization Model Considering Vehicle and Pedestrian Delays and Fuel Consumption Cost

Sustainability (2020)

Keyan Bai Enjian Yao Long Pan Linze Li Wei Chen

Due to the development of video perception technology, obtaining the volume of pedestrians and vehicles at a crosswalk has become much easier. Based on this development, this paper proposes a dynamic crosswalk signal timing optimization model and then analyzes the effects for three different signal timing strategies. First, we propose the dynamic signal timing optimization model by involving the delays of pedestrians and vehicles, as well as the fuel consumption cost, simultaneously. In the model, we design a dynamic signal timing strategy, using the volume of past cycles to predict the present volume, and then calculate the optimal signal timing by minimizing the total cost of the system. Second, the model is applied to a crosswalk in Beijing, China, as an example, and we compare and analyze the results of three timing strategies: Dynamic signal timing, optimal fixed timing, and current fixed timing. The results show that the dynamic signal timing is more efficient during the morning peak hour in terms of decreasing the total cost. Compared to the current fixed timing result, the vehicle delay and the fuel consumption decrease, while the pedestrian delay increases in both morning peak hour and flat hour for the other two signal timing strategies.

Schema crosswalk

Signal timing

SIGNAL (programming language)

10.3390/su12020689

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Citations (7)

Raman spectra of some carboxylic acids

Proceedings / Indian Academy of Sciences (1940)

Keyan Bai

10.1007/bf03046550

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Citations (9)

The ultra-violet absorption spectrum of diamond

Proceedings / Indian Academy of Sciences (1944)

Keyan Bai

Ultra violet

10.1007/bf03173451

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Citations (12)

Reducing intersystem crossing rates of boron emitters for high-efficiency and long-lifetime deep-blue OLEDs

Journal of Materials Chemistry C (2023)

Keyan Bai Mengke Li Xiaofeng Tan Lei Dai Kaichun Liang

An external quantum efficiency of 6.7% and a long operational lifetime of 136 h at 1000 cd m −2 were simultaneously realized for organic light-emitting diodes based on the deep-blue boron emitter (B-N-S-3), owing to the reduced intersystem crossing rate of the emitter.

Intersystem crossing

Quantum Efficiency

10.1039/d3tc03025c

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Citations (4)