Optimization of the theoretical photosynthesis performance and vision-friendly quality of multi-package purplish white LED lighting

Abstract

This study introduces the new figures of merit for photosynthesis and photo-pigmentation performance as well as vision performance for photosynthetically efficient, vision-friendly and tunable greenhouse LED lighting sources. The recently developed figures of merit, i.e., the photosynthetic luminous efficacy of radiation (PLER, plm W⁻¹), the photosynthetic luminous efficacy (PLE, plm W⁻¹), the photosynthesis illuminance (PIL), and the photosynthesis action factor (PAF) are measured and added to the measurements of the widely used figures of merit of vision and color to compare the four-package white LEDs developed by our group with natural sunlight and the presently commercialized artificial lamps for greenhouse or indoor use. In this study, one of the best selections of various four-package white LEDs (λ = 630, 590, 520, and 450 nm) shows excellent photosynthetic performance (PLER = 469 plm W⁻¹, PLE = 169 plm W⁻¹) and good vision performance (LER = 271 lm W⁻¹, LE = 98 lm W⁻¹, CRI = 86) at 10 000 K correlated color temperature (CCT) of blue-enriched white LED. Furthermore, this four-package white LED provides the tunable capability of the spectral power distribution (SPD) of lighting and excellent photosynthetic performance (PLER > 457 plm W⁻¹, PLE > 157 plm W⁻¹) even at eye-friendly vision performances (LER > 249 lm W⁻¹, LE > 87 lm W⁻¹, CRI > 85) under purplish emitting conditions. It can be expected that the four-package purplish white LEDs based on LPDF-capped, phosphor-converted monochromatic LEDs satisfy the requirements to attain high photosynthetic efficiency for the improved growth of plants, energy savings, vision-friendliness, and tunable figures of merit for the four-package LED lighting in greenhouses.