The electro-optical properties of materials included in the solar cell based on non-crystalline technical silicon have been investigated. It has been determined to what extent they are suitable as effective components of a nano-hetero-junction for converting radiation energy into electricity. The main factors that prevented the active use of technical silicon have been determined: the absence of free current carriers, weak electrical conductivity, a high degree of structurelessness, and the presence of a sufficiently high concentration of deep LDES – local defect energy states. It has been concluded that electrons in these deep states can contribute (and this is very important!) to the emergence of a nano-scale electric contact field. The special advantages of non-crystalline silicon with a rich LDES content as an effective material for a solar cell have also been revealed. It has been noted that these qualities of non-crystalline silicon, however, manifest themselves in the nanosized state only in combination with nano-crystalline lead chalcogenides PbX, where X can also be sulfur (S), selenium (Se) and tellurium (Te). An important conclusion of the work is also that similar positive transformative electro physical properties are characteristic of many semiconductors in the nano-sized state, if the energy spectrum of their electrons is similar to the spectrum in the nano-sized intrinsic crystalline semiconductor. It is proven that this contact field is formed due to the self-organizing growth of “islands” – crystalline nano-inclusions of PbX in places where с-PbX itself naturally finds a silicon nano-crystallite (с-Si) with a virtually identical crystalline structure (this is the peculiarity of self-organizing growth!) with the subsequent formation of ⟨с-Si::с-PbX⟩ – a nano-hetero-junction. The contact field parameters are calculated; the number N of electrons forming the contact field is determined; a numerical analysis of the electro physical parameters of the nano-hetero-junction is carried out.