Quantum dots (QDs) are semiconductor nanocrystals with remarkable optoelectronic properties as nanoscale materials. Their size-dependent electronic structure enables perfect tailoring to their desired optical characteristics, which is highly sought in high-resolution display devices and ultra-sensitive photodetector devices. This chapter discusses the latest breakthroughs in QD technology and focuses more on its new applications and influence on the fields in which they are applied. QDs are revolutionizing the very science of display technology with their vibrant color purity, wider color gamuts, and much greater energy efficiency than conventional LEDs. The chapter outlines QD-based displays from the very foundation of high-end consumer electronics, providing richer visuals and energy efficiency. In photodetectors, QDs enhance sensitivity over a wide range of ultraviolet to near-infrared spectral range, making them highly suitable for security, monitoring of the environment, and medical diagnostics. There is an emphasis on the application of QD photodetectors as a part of medical imaging devices for scanning in cases of COVID-19. The chapter sheds light on the use of QDs as part of photodetection technology, opens up possibilities for real-time monitoring devices with a high degree of accuracy but on a scale large enough to perform actual testing on a mass population, thus the significance of QDs in pandemic response situations. The chapter discusses and shows where problems may lie when the photodetectors are accomplished without stability, high performance for QD-based photodetectors, environmental stability, quantum yield, and device architecture. This chapter highlights new approaches and innovations in printed QD-based photodetectors and displays that are contributing toward the advancement of multifunctional, energy-efficient devices.