Among the effective use of solar energy, solar photovoltaic lighting systems are the fastest growing and most dynamic research field in recent years. Solar energy is a kind of radiant energy. The solar lighting system is used to directly convert sunlight into electrical energy to provide lighting appliances. It can only be achieved with the…
Solar energy and its comparison to conventional energy
The sun is a huge, long-lasting, and endless energy source. Solar energy is both a primary energy source and a renewable energy source. Solar energy is rich in resources, can be used free of charge, does not require transportation, does not pollute the environment, and has the advantages of energy saving, environmental protection, and convenience….
Thermal properties, luminous quality performance and limit parameters of LEDs
Thermal properties of LED The optical parameters of the LED have a great relationship with the junction temperature of the PN junction. Generally, the temperature rise of the LED is not obvious when the LED is continuously lit for a long time at a small current IF<10mA or 10-20mA. If the ambient temperature is high,…
Luminous brightness level development and life calculation of LED
1. Luminous brightness Brightness is an important parameter of LED luminous performance. It means that the surface brightness of the luminous body in a certain direction is equal to the luminous flux radiated by a unit projected area on the luminous body’s surface in a unit solid angle. The unit of brightness is cd/m2. The…
Luminous flux, luminous efficiency and visual sensitivity of LED optical properties
1. Luminous flux Luminous flux Φ is the radiant energy that characterizes the total light output of the LED, and it marks the performance of the device. Φ is the sum of the energy that the LED emits in all directions, and it is directly related to the working current. As the current increases, the…
Luminescence peak wavelength and spectral distribution of optical properties of LEDs
The light emitted by the LED is not a single wavelength, and its wavelength is basically distributed as shown in Figure 1. It can be seen from Figure 1 that no matter what material is used for the LED, the spectral distribution curve of the LED has the strongest relative light intensity (the maximum light…
LED luminous intensity and its angular distribution
The luminous intensity of an LED is a characterization of its luminous intensity in a certain direction. Since the luminous intensity of the LED differs greatly in different spatial angles, it is necessary to study the luminous intensity distribution characteristics of the LED. This parameter is of great practical significance and directly affects the secondary…
Electrical characteristics of LED
1. I-V characteristics. The I-V characteristic is the main parameter that characterizes the performance of the PN junction of the LED chip. The I-V characteristic of the LED has nonlinearity and unidirectional conductivity, that is, the applied positive bias voltage is low resistance, and vice versa, it is high resistance, as shown in Figure 1….
The luminous efficiency of LED
The luminous efficiency of the LED is generally called the external quantum efficiency of the module, which is the product of the internal quantum efficiency of the module and the extraction efficiency of the module. The so-called internal quantum efficiency of a module is actually the electro-optical conversion efficiency of the module itself, which is mainly related to…
The light-emitting principle of LED
LED is made of III-V compounds, such as GaAs (gallium arsenide), GaP (gallium phosphide), GaAsP (gallium arsenide phosphorous) and other semiconductors, and its core is a PN junction. Therefore, it has the I-V characteristics of a general PN junction, that is, forward conduction, reverse cutoff, and breakdown characteristics. In addition, under certain conditions, it also…