Choosing a Method for Approximating the Spectral Distribution of Colour LEDs and Comparing their Parameters and Characteristics in Nominal Mode

Abstract

New technologies and new light sources make it possible to create fundamentally new approaches in the design and construction of lighting devices. Light emitting diodes (LEDs) are a relatively new, promising and energy-efficient light source with a few unique properties: long lifetime, high luminous efficiency, aesthetics, environmental friendliness, reliability, high durability, and possibility to create a variety of spectra easily. During the lighting devices development, it is convenient to use mathematical approximations of the spectral distributions of the used LEDs in the composition of the product to calculate the final spectrum of the device in the visible range. These calculation methods are particularly interesting in architectural lighting. They are also applicable to the development of modern LED greenhouse irradiators. The article considers two main methods for approximating the emission spectra of colour LEDs: via symmetric and asymmetric distribution. The spectral distributions of four main types of LEDs that are used in the lighting devices design based on colour LEDs were measured in a wide range of currents from 100 mA to 1000 mA: red, amber, green, and blue. The results were also compared with a model that considers the two-dimensional density of states and potential fluctuations in the active region of the heterostructure of LED. Based on the carried-out measurements and calculations, the optimal approximation method via the asymmetric spectral distribution of LED radiation was determined.