Application Of Cadmium Oxide Electron Transport Layer In Antimony Selenide Solar Cells

Antimony selenide（Sb₂Se₃）thin film solar cells have attracted more and more attention due to their rich raw materials,stable structure and excellent photoelectric characteristics.Through recent development,the conversion efficiency of Sb₂Se₃ solar cells has been rapidly improved,but there is still a big gap compared with CdTe solar cells or perovskite solar cells.Therefore,it is necessary to more in-depth explore methods to improve the photoelectric performance of Sb₂Se₃ solar cells.In this paper,the application of CdO electronic transport layer in Sb₂Se₃ solar cells is explored,and the influence of CdO electronic transport layer preparation conditions and CdCl₂ processing on carrier transport characteristics of devices is analyzed.The high performance Sb₂Se₃ solar cells with CdO electronic transport layer are explored.The main research contents of this paper are as follows:（1）The influence mechanism of electron transport layer parameters on Sb₂Se₃ solar cells was revealed by optimizing the energy level distribution,defect state,electron mobility and doping concentration of electron transport layer in Sb₂Se₃ solar cells.When the electron affinity is lower than 4.0 e V and higher than 4.4 e V,the carrier transport capacity is lower and the recombination rate of Sb₂Se₃ layer is higher.Therefore,the electron affinity between 4.0 e V and4.4 e V has high performance of Sb₂Se₃ solar cells.The increase of defect states will reduce the carrier transport capacity of the electron transport layer and slow down the band structure of Sb₂Se₃ layer,,which should not be higher than 10¹⁸ cm^-3.When the electron affinity and defect state are 4.2 e V and 10¹⁸ cm^-3 respectively,the photoelectric conversion efficiency is 13.16%.The increase of electron mobility can reduce the carrier accumulation at the Sb₂Se₃ front end,and then reduce the carrier recombination rate between the electron transport layer and Sb₂Se₃front end.When the electron mobility exceeds 10^-1 cm~2V^-1s^-1,the photoelectric conversion efficiency can reach more than 13%.When the doping concentration reaches 10¹⁸ cm^-3,the front-end carrier concentration of the electron transport layer and Sb₂Se₃ layer is higher,and the long-wave response is enhanced.If the electron mobility is lower than 10^-1 cm~2V^-1s^-1 and the doping concentration is above 10¹⁹ cm^-3,doping treatment can make up for the lack of mobility of electron transport laye,and the device conversion efficiency above 13.09%can still be achieved.The simulation study can point out the direction for the optimization of the electron transport layer and provide guidance for the application of CdO electron transport layer in Sb₂Se₃ solar cells.（2）The Sb₂Se₃ solar cell of CdO electronic transport layer was constructed for the first time.The best preparation and treatment conditions of CdO electron transport layer were studied experimentally to improve the battery performance.Firstly,the CdO film prepared by spray pyrolysis of Cd（CH₃CO₂）₂ aqueous solution has higher conductivity（compared with CdCl₂）,and the Sb₂Se₃ film grown on it has stronger vertical preference and less carrier recombination.Then,the best experimental conditions for the preparation of CdO thin film with Cd（CH₃CO₂）₂aqueous solution as cadmium source were explored.The study shows that the best morphology and conductivity of CdO film can be obtained by spraying Cd（CH₃CO₂）₂ aqueous solution with0.3 M at 300℃ and 0.5 m L/min for 20 min.The Sb₂Se₃ layer on it was dense and had better preferred orientation.The photoelectric conversion efficiency of 3.20%can be obtained.Finally,CdCl₂ was used to deal with the CdO electronic transport layer,which passivated the CdO/Sb₂Se₃ interface defect,optimized and regulated the Sb₂Se₃ growth orientation,and achieved the best conversion efficiency of 4.46%.This study provides a low-cost method to improve the performance of Sb₂Se₃ solar cells in the electronic transport layer of CdO,and provides technical support for the development of Sb₂Se₃ solar cells.