Local Light Field Control Enables Efficient Quantum Dot Color Conversion Films for Mini‐LED Backlit Displays

Quantum dot (QD) color conversion films (QD‐CCFs) are used in ultrahigh definition (UHD) Mini‐LED backlit displays due to their narrow band emission and high color purity. However, their poor light conversion efficiency (LCE) leads to greater film thickness and thus high cost. Herein, this study proposes a local light field control strategy to enhance the LCE of QD‐CCFs using high‐refractive BN nanosheets. The LCEs of the green and red QD‐CCFs can increase from 29.9% and 34.8% to 67.4% and 91.0% after adding BN nanosheets, respectively. Combining the experimental data with the finite‐difference time domain (FDTD) simulations, the enhanced LCEs can be attributed to observably increased blue light absorption and improved light extraction efficiency of the light emitted from QDs. The white Mini‐LEDs, prepared by integrating the optimized QD‐CCFs containing BN nanosheets with blue Mini‐LED chips, show a high luminous efficiency of 70.2 lm W−1, a high external quantum efficiency of 36.2%, and a wide color gamut of 96.3% Rec. 2020 standards. This work provides an interesting idea for designing high‐efficiency QD‐CCFs toward low‐cost UHD Mini‐LED backlit displays.