Разработка высоковольтных матричных солнечных элементов с высокой эффективностью

Development of high voltage matrix solar cells with high efficiency V. Borisov, V. Polyakov All Russian Scientific Research Institute for electrification of agriculture, Moscow    At present, the efficiency of the silicon matrix solar elements, in foreign classification – VMJ SC (vertical multi-junction solar cell) at the concentrated sunlight makes 25 %. In this work VMJ manufacturing techniques with the efficiency exceeding the reached level is considered. Particular attention is paid to methods of passivation of converters. Application of passivation by alumina, obtained by atomic layer deposition (ALD),  with a negative charge at the interface Al 2 O 3 -Si leads to a decrease of the rate of recombination of photogenerated minority carriers and to increase current sensitivity VMJ SC with consistently connected n + -p -p + structures. However the effect of field passivation weakens because of existence on a surface before atomic layer deposition of a layer of nonequilibrium "dirty" oxide. Heat treatment of a surface of VMJ in oxygen before drawing thin (10-15) nanometers of a layer of alumina with the subsequent his growing to thickness corresponding to the first order of an enlightenment on the wavelength of 0,6 microns - (85-90) nanometers, and the corresponding heat treatment lead to stabilization of Al 2 O 3 -Si interface. The main layer of oxide of aluminum is besieged from colloidal - disperse Al 2 O 3 solution in water.   VMJ are exposed to heat treatment in the atmosphere of nitrogen for the purpose of homogenization of structure of the put covering: at first at a temperature of 130C within 1 hour, then at a temperature of 60 C within 6 hours.   Application of a combined method of putting oxide of aluminum allows to receive steadily coverings with the following parameters: the coating thickness of 85-90 microns, a refractive index of 1.65-1.70, surface charge  and surface recombination velocity, respectively - - (0.8-1.0) 10 13 kul /cm 2 and (100-120) cm /s. The quantum yield of the photoelectric effect VMJ SC  combined alumina coating in the field of short lengths of waves (0.4-0.5) ) microns greater than 1. The integrated value of reflectance in a wavelength range (0,35-1,15) microns was no higher than 2,8 %. The conversion efficiency of   VMJ SC with alumina coating and concentrator modules on their basis in illumination range (50-500) kW / m 2 in the atmospheric conditions of AM 1.5 was in the range (23-26) %. Best  matrix  receiver amounted conversion efficiency 29.26 % at 56-fold concentration of the sunlight.