Comparison between blue lasers and light‐emitting diodes for future solid‐state lighting

TLDR

Solid‑state lighting delivers the most efficient, high‑color‑quality white light, yet blue InGaN LEDs suffer from efficiency droop at high current densities, limiting photon output per chip area and raising costs. The study proposes blue laser diodes as a potential alternative to mitigate droop and examines LEDs and LDs for future SSL by comparing their power‑conversion efficiencies, peak performance improvements, and economic viability. The authors compare current state‑of‑the‑art input‑power‑density‑dependent efficiencies, potential gains in peak efficiencies and optimal input power densities, and the economics of LEDs versus LDs for practical SSL.

Abstract

Abstract Solid‐state lighting (SSL) is now the most efficient source of high color quality white light ever created. Nevertheless, the blue InGaN light‐emitting diodes (LEDs) that are the light engine of SSL still have significant performance limitations. Foremost among these is the decrease in efficiency at high input current densities widely known as “efficiency droop.” Efficiency droop limits input power densities, contrary to the desire to produce more photons per unit LED chip area and to make SSL more affordable. Pending a solution to efficiency droop, an alternative device could be a blue laser diode (LD). LDs, operated in stimulated emission, can have high efficiencies at much higher input power densities than LEDs can. In this article, LEDs and LDs for future SSL are explored by comparing: their current state‐of‐the‐art input‐power‐density‐dependent power‐conversion efficiencies; potential improvements both in their peak power‐conversion efficiencies and in the input power densities at which those efficiencies peak; and their economics for practical SSL.