Generating electrical energy with shadow: Shadow Effect Generation (SEG)

Energy generator with shadow effect generates electricity using the contrast between illuminated and shaded areas.

Shadows are often associated with darkness and uncertainty. Researchers at the National University of Singapore (NUS) have given the shadows a positive perspective by showing a way to use this common but often overlooked optical effect to generate electricity. This concept brings new approaches to power electronics in green energy production under indoor lighting conditions.

Tan Swee Ching, Assistant Professor leader of the research team from the NUS Materials Science and Engineering Department:
“Shadows are everywhere. In traditional photovoltaic or optoelectronic applications where a constant light source is used to power devices, the presence of shadows is undesirable because it degrades the performance of the devices. In this study, we used the contrast contrast caused by shadows as an indirect power source. Contrast in lighting, “This new concept, which collects energy in the presence of shadows, is an unprecedented study,” causing a voltage difference between the shadowed and illuminated sections.

Mobile electronic devices such as smartphones, smart glasses and e-watches require efficient and continuous power supply. As these devices are worn both indoors and outdoors, wearable power supplies that can take advantage of ambient light can potentially increase the versatility of these devices. While commercially available solar cells can perform this role outdoors, energy harvest efficiency drops significantly as shadows are permanent in indoor conditions. This new approach to generating energy from both lighting and shadows associated with low light intensities to maximize the efficiency of energy harvesting has been both exciting and timely, according to today’s conditions.

The NUS team has developed a low cost, easy to manufacture SEG to perform two functions:

In stage 1, it converts the lighting contrast in partial shaded plates into electricity, it functions as a self-powered proximity sensor for tracking objects passing in stage 2.

SEG consists of a series of SEG cells arranged on a flexible and transparent plastic film. Each SEG cell consists of a thin gold film placed on a silicon sheet. Carefully designed, SEG can be produced at a lower cost compared to commercial silicon solar cells. The NUS team then conducted a series of experiments to test SEG’s performance in electricity generation and as a self-powered sensor.

The explanation of Professor Andrew Wee, co-team leader from the NUS Physics Division, is as follows: “When the entire SEG cell is in the light or in the shade, the amount of electricity produced is very low or absent. When some of the SEG cell is illuminated, a significant electrical output has been detected. half of the SEG cell must be illuminated for the highest level of production, while the other half must be in the shade, as this provides enough space for charge generation and collection. “

According to laboratory experiments, the four-cell SEG produced by the team turned out to be twice as efficient under commercial silicon solar cells under the influence of changing shadows. In the presence of shadows created in indoor lighting conditions, the energy generated from SEG produces enough energy to operate a digital clock (i.e. 1.2 V).

In addition, the team has shown that SEG can be used as a self-powered sensor to track moving objects. When an object passes past the SEG, it drops an intermittent shadow on it and triggers the sensor to record the object’s presence and movement.

Work continues for lower cost and more functionality

The team of six has worked for four months to conceptualize, develop and perfect the performance of the device. In the next phase of the research, the NUS team stated that they will try other materials besides gold to reduce the cost of SEG.

NUS researchers are also considering developing self-operating sensors with versatile functions and SEGs that can be used in clothes to generate energy during normal daily activities. Another promising research area is the development of low-cost SEG panels to efficiently generate energy from indoor lighting.