**Abstract**

A thermoelectric control system using thermoelectric cooler devices (TEC) combined with an aluminum heat dissipater and a fan heat extractor allows improving considerably the optical performance of deep UV LEDs (285 nm) operating at desired temperatures. A proportional, integral, and differential controller (PID) control technique was implemented to control the voltage in the TEC devices, and therefore, the desired range of temperatures can be achieved. The PID parameters are obtained with computational simulations based on physical models and experimental data recordings of the temperature, using a thermistor sensor for the temperature measurements and SiC photodiode with UV enhanced system for the optical power measurements. The experimental data show that decreasing the temperature of the UV-C LED light source using a TEC increases the optical output power, while it has been shown that the lifetime of the LED devices can be improved.

**Keywords:** thermoelectric cooler, optoelectronics, ultraviolet, light-emitting diode, temperature

## **1. Introduction**

Manufactures of new solid state light sources have focused the attention to deep UV light sources (200–300 nm), where UV-C LEDs (or deep UV-LEDs) have shown great potential in many technological applications, such as water and surface disinfection processes, biomedical instrumentation systems, high density optical recording, lithographic micro fabrication, and biophotochemical research [1–4]. The complexity of a reliable UV-C LED performance depends upon optical efficiency, adequate lifetime, and wavelength accuracy that all concern technological applications. It is known that the UV-C LEDs have lower external quantum efficiency (EQE) with a value less than 10%, compared with conventional LED light sources, for example, blue LED (400–450 nm) has an EQE > 70%. In microbiological research, the shift of the peak wavelengths would result in an inaccurate interpretation in microbial studies [5].
