Transparent conductive oxide(TCO)thin films are highly desired as electrodes for modern flat-panel displays and solar cells.Alternative indium-free TCO materials are highly needed,because of the scarcity and the high ...Transparent conductive oxide(TCO)thin films are highly desired as electrodes for modern flat-panel displays and solar cells.Alternative indium-free TCO materials are highly needed,because of the scarcity and the high price of indium.Based on the mechanism of resonant doping,Ta has been identified as an effective dopant for SnO_(2)to achieve highly conductive and transparent TCO.In this work,we fabricated a series of Ta-doped SnO_(2)thin films(Sn_(1-x)Ta_(x)O_(2),x=0.001,0.01,0.02,0.03)with high conductivity and high optical transparency via a low-cost sol-gel spin coating method.The Sn_(0.98)Ta_(0.02)O_(2)film achieves the highest electrical conductivity of 855 S cm-1with a carrier concentration of2.3×10^(20)cm^(-3)and high mobility of 23 cm^(2)V^(-1)s^(-1).The films exhibit a very high optical transparency of 89.5%in the visible light region.High-resolution X-ray photoemission spectroscopy and optical spectroscopy were combined to gain insights into the electronic structure of the Sn_(1-x)Ta_(x)O_(2)films.The optical bandgaps of the films are increased from 3.96 eV for the undoped SnO_(2)to 4.24 eV for the Sn_(0.98)Ta_(0.02)O_(2)film due to the occupation of the bottom of conduction band by free electrons,i.e.,the Burstein-Moss effect.Interestingly,a bandgap shrinkage is also directly observed due to the bandgap renormalization arising from many-body interactions.The double guarantee of transparency and conductivity in Sn_(1-x)Ta_(x)O_(2)films and the low-cost growth method provide a new platform for optoelectronic and solar cell applications.展开更多
基金supported by the National Natural Science Foundation of China(21872116 and 22075232)。
文摘Transparent conductive oxide(TCO)thin films are highly desired as electrodes for modern flat-panel displays and solar cells.Alternative indium-free TCO materials are highly needed,because of the scarcity and the high price of indium.Based on the mechanism of resonant doping,Ta has been identified as an effective dopant for SnO_(2)to achieve highly conductive and transparent TCO.In this work,we fabricated a series of Ta-doped SnO_(2)thin films(Sn_(1-x)Ta_(x)O_(2),x=0.001,0.01,0.02,0.03)with high conductivity and high optical transparency via a low-cost sol-gel spin coating method.The Sn_(0.98)Ta_(0.02)O_(2)film achieves the highest electrical conductivity of 855 S cm-1with a carrier concentration of2.3×10^(20)cm^(-3)and high mobility of 23 cm^(2)V^(-1)s^(-1).The films exhibit a very high optical transparency of 89.5%in the visible light region.High-resolution X-ray photoemission spectroscopy and optical spectroscopy were combined to gain insights into the electronic structure of the Sn_(1-x)Ta_(x)O_(2)films.The optical bandgaps of the films are increased from 3.96 eV for the undoped SnO_(2)to 4.24 eV for the Sn_(0.98)Ta_(0.02)O_(2)film due to the occupation of the bottom of conduction band by free electrons,i.e.,the Burstein-Moss effect.Interestingly,a bandgap shrinkage is also directly observed due to the bandgap renormalization arising from many-body interactions.The double guarantee of transparency and conductivity in Sn_(1-x)Ta_(x)O_(2)films and the low-cost growth method provide a new platform for optoelectronic and solar cell applications.
