Design And Photoelectric Performance Of Semiconductor Nanowall Arrays

As an important means of supplying clean electricity,photovoltaic power generation has an inexhaustible source of energy,wide distribution and environmental friendliness.It is one of the feasible strategies to achieve long-term sustainable development goals.To expedite the goal that uses solar power to generate electricity,further improvement of the performance-to-cost ratio is appreciated for photovoltaic?PV?panels,Improving the efficiency of solar cells and reducing the cost of manufacturing are two main schemes to improve the cost performance ratio of solar cells,reducing quantity and quality dependency of the active materials can effectively reduce the manufacturing cost of solar cells.As a new photovoltaic device to alleviate the energy crisis,thin film solar cells use less materials than high-cost crystalline silicon solar cells.The short carrier collection length makes the devices less dependent on the quality of materials,and can be manufactured using cheap glass,plastics,ceramics and other materials as substrates.In this paper,two kinds of light trapping structures compose of‘U'pool?shaped nanowall array and inverted‘U'pool?shaped nanowall array were investigated regarding light management and photoelectric conversion behaviors based on gallium arsenide?GaAs?and polycrystalline silicon?poly?Si?.The main research contents are as follows:?1?The effects of substrate thickness?T?,width?W?and height?H?on the optical properties of"U"shaped walls were studied based on gallium arsenide?GaAs?and polycrystalline silicon?poly?Si?materials.For GaAs materials,Studies have shown that exhibits excellent light confinement can be realized in a broad range of the structural parameters.the nanowall with T=100 nm,W=500 nm,and H=1000 nm can produce a photocurrent of 29.0 mA/cm².i.e.,⁹3.5%absorption of incident photons with energy larger than 1.42 eV.As a distinct comparison,a 2000 nm thick flat GaAs film only delivers J_ph of¹9.8 mA/cm² under the same illumination.Photoelectric simulations indicate that device performance is not sensitive to bulk recombination,and however appropriate surface passivation of reducing the recombination velocity to the order of¹0² cm/s is necessary for achieving a high power conversion efficiency.²0.8%power conversion efficiency is predicted for the proposed structure with an effective thickness of only³15 nm when the bulk carrier mean lifetime and surface recombination velocity are 10^-4 s and10² cm/s.Due to the excellent omnidirectional light management properties of the structure,even at a large angle of incidence of 60°,the structure can maintain 90%light absorption.?2?The inverted“U”shaped wall has also been studied in the same parameter range.Compared with the“U”shaped wall,it's reflected light is more serious,but it still has good light trapping performance.The GaAs nanowall with T=0 nm,W=650nm and H=2000 nm can generated a photocurrent of 28.87 mA/cm² with effective thickness about 1570 nm.The light absorption is increased by about 30%compare to planar GaAs solar cell with a thickness of 2000 nm.Since the photo-generated carriers are mainly distributed on the top of the inverted"U"shaped wall,while the bottom of"U"shaped wall and the inside of substrate have more carriers,therefore,although their conversion efficiency are nearly equal when not considering any carrier recombination,as the carrier lifetime decreases,the former's electrical performance decreases more quickly.