Zn doping induced optimization of optical and dielectric characteristics of CuInSe2 nanosheets for optoelectronic device applications

The ternary chalcopyrite CuInSe2 (CIS) has recently gained significant attention due to its potential appli-cations in various optoelectronics and photonics devices. Here, the CIS nanosheets with different Zn doping content were synthesized by a simple hot injection method. The undoped CIS showed pure crystallinity, while Zn incorporation led to the enhancement of the amorphous nature inside the matrix. A shift in the diffraction pattern and Raman vibrational bands with varying Zn content suggests the doping-induced structural rearrangements inside the system. Morphological study deliberates the transit from clean proper CIS nanosheets to pigmented patterns due to doping. The Zn doping in the CIS lattice causes the insertion of the more intermediate levels within the band gap that enhances the optical absorption. The variation of the absorption edges with doping content tends to decrease the optical band gap by creating more disorder and defects in between the gap region. Broad absorbance over visible and NIR region and reduction in Eg favours in the application of an absorber layers in solar cells. Broad photoluminescence emission is observed for all the cases with 514 nm excitation. Each spectrum is comprised of four component peaks corresponding to the transition between different intermediate levels. The dielectric behaviour as a function of frequency and temperature was investigated, and the results showed improved conductivity with reduced dielectric loss. The dielectric constant and tangent loss decreased with frequency and improved with increasing tem-perature. The improvement of AC conductivity with temperature concludes the increase in the mobility of charge carriers that are responsible for hopping and electronic polarization. The observed optical and di-electric properties are quite suitable for various photonics, memory devices. electro-optic devices and their applications. (c) 2023 Elsevier B.V. All rights reserved.

Automated summary

In this study, CuInSe2 (CIS) nanosheets with different Zn doping content were synthesized using a simple hot injection method. The introduction of Zn led to the amorphous nature inside the CIS matrix and structural rearrangements in the system. The Zn doping also enhanced optical absorption and decreased the optical band gap, making the material suitable for solar cell applications. The observed broad absorbance and photoluminescence emission, as well as improved dielectric properties, suggest the potential of CIS for various optoelectronics and photonics devices.