Research On Quantum Electromagnetic Analysis Methods Of Nano-scale Photovoltaic Devices

With the continuous advancement of science and technology,the efficiency and demand for energy utilization are constantly increasing,which provides a great stage and opportunity for the development of photovoltaic devices.However,on a nanoscale,theoretical prediction of performance of photovoltaic devices is a difficult task.The challenge mainly comes from the fact that the optical and electronic properties of the nanoscale structures need to be described at a high level of accuracy,and the atomistic details have important effects on the performance of devices.Traditional photovoltaic device simulations are mostly based on classical models,which relies only on empirical parameters,but ignores atomistic details and quantum mechanical effects.Therefore,how to study more accurately nanostructured photovoltaic devices is of great significance.In order to accurately and efficiently analyze the performance of nanostructured photovoltaic devices,a quantum mechanics/electromagnetics(QM/EM)method based on density functional tight-binding theory(DFTB)and non-equilibrium Green's function theory(NEGF)is adopted in this work.The method is described by the classical electromagnetic theory in an electromagnetic environment which is part of the photovoltaic device,and the photovoltaic device is coupled by the secondary quantization of the field.Finally,the optical and electrical characteristics of the photovoltaic device are obtained by the full quantum first-principles calculation.In this work,the quantum electromagnetic method is applied to the performance research of silicon nanowire photovoltaic devices and plasmon-enhanced silicon nanowire photovoltaic devices.Based on the density functional tight-binding theory,photovoltaic devices are simulated without relying on empirical parameters,and the current-voltage characteristics and optical properties are simulated.The results show that: Firstly,the fine arrangement and non-equilibrium conditions at the atomic level have a significant effect on the photoresponse of the device.Secondly,the local surface electric field enhancement effect of the nanometal structure significantly enhances the energy conversion efficiency of the photovoltaic device.This method adopted in this work shows significant advantages in the design and optimization of nanoscale photovoltaic devices.