The shadow-effect energy generator (SEG) created by the researchers consists of a set of SEG cells arranged on a flexible and transparent plastic film. Each SEG cell is made of a thin film of gold deposited on a silicon wafer and can be fabricated at a much lower cost compared to commercial silicon solar cells. The contrast in illumination induces a voltage difference between the shadow and illuminated sections, resulting in an electric current.
The research breakthrough, published in the Energy & Environmental Science journal under the title “Energy harvesting from shadow-effect”, reports that such a SEG is capable of harvesting energy from illumination contrasts arising even under weak ambient light. Without any optimization, the proof-of-concept generator exhibited a power density of 0.14μW cm−2 under indoor conditions (0.001 sun) where shadows are persistent. The authors also claim that the SEG performed at twice the efficiency of commercial silicon solar cells under the effects of shadows.