How Light Emitting Diodes (LEDs) Work

When a forward voltage is applied to a PN junction formed by some semiconductor materials, holes and electrons will generate light of a specific wavelength when they recombine at the PN junction. The wavelength of the emitted light is related to the energy level gap Eg of the semiconductor material: λ＝hc / Eg

The relationship between the output light power P of the light-emitting diode and the driving current I is: P = ηEp I/ e. This experiment uses a red ultra-high brightness light-emitting diode with adjustable driving current as the experimental light source.

Determination of the relationship between the photocurrent and the input light signal of the silicon photocell at zero bias and reverse bias
Connect the output end of the silicon photocell to the input end of the I/V conversion module, connect the output end of the I/V conversion module to the input end of the digital voltmeter, adjust the static drive current of the light-emitting diode, and measure the relationship between the photocurrent and the input light signal of the photocell at zero bias and reverse bias. Measure 10 sets of data at equal intervals within 5~15mA. Compare the two curves at zero bias and reverse bias to find the saturation current Is of the photocell.

Determination of the relationship between the photovoltaic voltage and the input light signal when the output of the silicon photovoltaic cell is connected to a constant load

Turn the function conversion switch to "load", connect the output end of the silicon photovoltaic cell to a constant load resistor (R is 1KΩ and 10KΩ respectively) and a digital voltmeter, adjust the static drive current of the light-emitting diode, and measure the relationship between the photovoltaic cell output voltage and the input light intensity.
Determination of the volt-ampere characteristics of silicon photovoltaic cells When the input light intensity remains unchanged (the drive current is 5 mA and 15mA respectively), measure the relationship between the photovoltaic cell output voltage and the load resistance when the load changes in the range of 0.5kΩ to 9.5kΩ.