Indoor Photovoltaics

Photovoltaics can be used indoors, among other things, to supply sensors or electronic components of the “Internet of Things (IoT)” with electrical energy. Although the required amounts of energy are typically rather small, indoor PV offers advantages in terms of cost and sustainability, e.g., by avoiding battery waste.

In contrast to sunlight, artificial light sources have a much narrower spectrum that is optimized for the human eye. For this reason, the optimal band gap of the active semiconductor for indoor solar cells is about 1.7-1.9 eV. This makes crystalline silicon  a less suitable material. In contrast, amorphous  silicon technology currently dominates themarket, but alternative technologies such as dye solar cells, organic and perovskite solar cells, and thus potentially extremely cost-effective technologies, are entering the market. Despite their higher costs, III-V-based solar cells are also advantageous for certain applications due to their high efficiency and good low-light behavior, for example when  space available for energy generation is severely limited.

Although the market for indoor PV is limited due to the low amounts of energy required, it is still an interesting niche market due to the rapidly increasing number of elements of the “Internet of Things”. 

In this research area, we develop flexible and rigid solar modules made of organic, perovskite and III-V semiconductors and support our customers in designing them for their specific IoT applications.