Study Of Back Contact Interface Of The CdTe Thin Film Solar Cells

Cadmium telluride（CdTe）is an ideal material for the preparation of high-performance and low-cost solar cells.It is a direct bandgap semiconductor with a bandgap of 1.45 e V,which matches the solar spectrum at standard atmospheres（AM1.5）.The theoretical efficiency of CdTe solar cells could be 30%.In addition,CdTe has a high absorption coefficient of about 10⁵cm^-1in the visible light range,which is about 100 times higher than monocrystalline silicon.It also has good temperature coefficient and great weak-light performance.CdTe solar cells can be prepared by using very simple equipment and methods.At present,the laboratory efficiency of CdTe solar cell has reached 22.1%,and the efficiency of the small module has reached 18.6%.However,efficient CdTe solar cells still have many problems to be solved.This thesis focuses on the fundamental problems in the preparation of high efficiency and stable CdTe solar cells.The main work is as follows:（1）We modify and analyze the characteristics of ZnTe:Cu back contact in the CdTe solar cells.We regulate the back contact characteristics and device performance by subsequent heat treatment.Based on the characterization of material interfaces and devices,we analyze the change of the distribution of elements,phase structure,energy band structure,chemical states in the back contact interface during heat treatment procession.With the optimization of ZnTe:Cu preparation procession,we prepare CdTe solar cells with a conversion efficiency of 15.8%.（2）We study the CdTe solar cell with MgZnO/CdTe structure.In the experiment,MgZnO films with different Mg contents,thickness and atmosphere were prepared.And then we studied the influence on device performance.Additionally,we study the CdTe deposition procession which matched with MgZnO window layer by regulating CdTe growth temperature and rate.Based on the optimization,we prepared the optimal device with an efficiency of16.1%.