Simulation Study On Photoelectric Performance Of InGaN Solar Cell

The excellent photovoltaic properties of InGaN materials have attracted attention,it has tunable energy band gap varying from 0.64 to 3.42 eV.High absorption coefficient,high radiation resistance and other advantages,making InGaN solar cells have great development prospects.In this paper,a more systematic study and analysis of InGaN solar cells is conducted.1.Using numerical simulation methods to analyze the collection efficiency,I-V characteristics,built-in electric field and carrier transport of solar cells.Studying the influence of various parameters on the performance of InGaN p-i-n homojunction solar cells.Also explains its internal mechanism.It was found that the longer the lifetime of minority carriers,the higher the conversion efficiency of the solar cells.However,for low indium components,the lack of photo-generated carriers inside the device also limits the conversion efficiency.When the indium content is around 60%,the conversion efficiency to be optimal.When the front surface recombination rate is faster than 104 cm/s,the efficiency will decrease sharply.While the back-surface recombination rate even as high as 107 ca/s,it has no decrease for conversion efficiency.It was also found that the InGaN solar cell with different indium composition(x)should match different parameter values to obtain the highest conversion efficiency.Like InGaN solar cells with low indium composition,the p-type doping concentration can be lower,and the p-layer thickness can also be thinner.Increasing the p-layer hole concentration will make the efficiency of the InGaN solar cell increase first and then decrease slightly.When the hole concentration in the p-layer is very low,the decrease of collection efficiency and the increase in series resistance together lead to a decrease in conversion efficiency.The simulations also show that the thinner the p-layer thickness,the greater the proportion of lateral transport along the parallel to the p-n junction.At the same time,the lateral transport of carriers from the p-layer to the anode electrodes becomes more obstructive with the thinner p-layer thickness.When the p-layer thickness decreases,it causes p-layer sectional area decreases,so the lateral series resistance becomes larger.As the thickness of the p-layer becomes thinner,the increase in the lateral series resistance of the p-layer is the main reason for the decrease in conversion efficiency.2.Based on the homojunction,Optimized and analyzed the performance of InGaN heterojunction solar cells.It was found that the conversion efficiency of p-GaN/i-In0.6Ga0.4N/n-GaN heterojunction solar cells is very low due to the high interface barriers at the heterogeneous interface,leading to photo-generated carries have a recombination.The short-circuit current density of the heterojunction solar cell is increased from 0 to 27.6 mA/cm2 by inserting an indium gradient of 5%between GaN and In0.6Ga0.4N.The efficiency of graded-layer heterojunction solar cell is higher than that of homojunction solar cell,and the difference between graded-layer heterojunction solar cell and homojunction solar cell is larger with the increase of indium component.In the process of optimizing the heterojunction solar cell,it was also found that when the surface recombination rate is very large,the efficiency of the graded-layer heterojunction solar cell will not sharply decrease.Heterojunction solar cells are less sensitive to front surface defects than homojunction solar cells.3.The influence of temperature and Light intensity on the photoelectric performance of Vertical structure In0.35Ga0.65N/GaN MQWs solar cells is analyzed.It was found that the higher the temperature,the lower the conversion efficiency.Reduction rate of the conversion efficiency is 15.6%with the reduction of light intensity from 1 sun to 0.03 sun,while reduction rate of the silicon solar cells is 31.1%.Vertical structure In0.35Ga0.65N/GaN MQWs solar cells have better weak-light-performance than Si solar cells.The conversion efficiency will increase with the increase of electroluminescence wavelength(444 nm to 452 nm)of vertical In0.15Ga0.85N/GaN MQWs solar cells.