1：Experimental Design and Method Selection:

The study involved designing and synthesizing anthracene derivatives with different electron-donating and -withdrawing substituents to investigate their upconversion efficiency in OLEDs. Theoretical models and quantum chemical calculations were employed to understand the upconversion mechanism.

2：Sample Selection and Data Sources:

Anthracene derivatives were synthesized and purified by vacuum sublimation. Their structures were characterized by 1H and 13C NMR spectroscopies and elemental analyses.

3：List of Experimental Equipment and Materials:

UV–Vis spectrometer (Lambda 950; Perkin-Elmer), spectrofluorometer (FluoroMax-3, Horiba), another spectrofluorometer (FP-8600, JASCO), absolute PL quantum yield spectrometer (Quantaurus-QY, Hamamatsu Photonics), variable angle spectroscopic ellipsometry (M-2000U; J. A. Woollam Co., Inc.), transient PL decay measurement system (Quantaurus-Tau, Hamamatsu Photonics), absolute EQE measurement system (C9920-12, Hamamatsu Photonics), photomultiplier tube (R928; Hamamatsu Photonics), amplifier unit (C6438; Hamamatsu Photonics), pulse generator (8114A; Agilent), oscilloscope (TBS2104, Tektronix).

4：Experimental Procedures and Operational Workflow:

Thin films for optical measurements were fabricated by vacuum vapour deposition. OLEDs were fabricated on ITO-coated glass substrates by vacuum vapour deposition. Organic layers and electrodes were deposited at specified rates. Optical and electrical measurements were conducted to evaluate the performance of the OLEDs.

5：Data Analysis Methods:

The data were analyzed using theoretical models and quantum chemical calculations to understand the upconversion mechanism. The ratio of EL intensity generated by direct recombination and TTU was estimated from transient EL characteristics.