THE EFECT OF THE INTERFACE GRAIN BOUNDARIES ON THE OPTOELECTRICAL CHARACTERISTICS AT THE MULTILAYER HETEROSTRUCTURES BASED ON POLYCRYSTALLINE SILICON, II-VI COMPOUNDS AND PHOTOSYNTHETIC PIGMENTS

摘要

This paper presents the results of the experimental researches on the influence of the microcrystaline Chl films upon the electro-optical and photovoltaic properties in the case of an Al~+ nSi-nCdS-pChl-p~+Cu_xS:Cu_2O/Cu-type multilayer heterostructure. Being constituted from more series-superposed and vertically-illuminated semiconductor junctions, the respective photosystem allows the selective usage of a part as large as possible from the spectrum of the solar radiations which is of interest for the photovoltaic conversion. We also consider that the semiconductor materials which made up this heterostructure are able to accomplish a convenient and perfectible compromise between the "optimum material" criteria, on one hand, and the financial, economic and ecologic criteria, on the other hand. The paper also suggests a model for the diagram of the energetic bands in which we try to explain the complex mechanism of the carriers transport at the system interfaces - mechanism dominated in this type of structure by the trapping -recombining, tunneling and injection phenomena through the interfaces states of the "space charge limited current" (SCLC)-type. Thus, there have been found similitudes between the photoelectric behavior of this photosystem type and the specific electro-optical behavior of the electronical devices with "charge transfer" used as image sensors in the information optical processing.