The development of materials based on quantum structures (QS) in nanotechnology, and especially in photo-sensitive devices, belongs to one of the most important areas of scientific research. Semiconductor QS are known to have unique optical and electrical properties due to quantum confinement effects on the charge carriers in them. Therefore, their energy gap depends on the structure, shape and size of the QS, and it is possible to change it in a controlled manner. Confinement effects are particularly strong in core/shell QS where electrons and holes are often spatially separated. The next very significant effect is the generation of multiple excitons upon excitation by a single photon. Because of it, the degree of conversion of the incident photon into electrons (quantum efficiency) is greater than 100% for some photon energies. This effect is particularly significant for photosensitive devices.The main goal of the project is to use and develop the above-mentioned properties of photosensitive QS based on germanium for the production of efficient sensors, detectors, solar cells and devices for splitting water. Our research so far has resulted in a series of such materials composed of spatially ordered networks of Ge QS in various dielectric matrices. These materials include 3D networks of Ge, Ge/Si and Ge/metal core/shell quantum dots and Ge quantum wires. They show an energy gap in the range of 0.7 - 3 eV, absorption in the IR to UV region, a very strong photo-generated current (light/dark ratio over 10^5), and an extremely pronounced multiple exciton generation effect, in addition to a very interesting structure. In addition, these QSs are immersed in matrices, and are very stable and harmless to health.This research relays on materials that are excellent in all their properties for use in photo-sensitive devices. Their application is still completely unexplored. Our advantage is that we have developed them, so we know how to prepare and characterize them.