Morphological, Photoluminescence, and Electrical Measurements of Rare-Earth Metal-Doped Cadmium Sulfide Thin Films

Muhammad Azhar ¹, Ghazi Aman Nowsherwan ¹, Muhammad Aamir Iqbal ²

⁰Centre of Excellence in Solid State Physics, University of the Punjab, Lahore 54590, Pakistan.

Acs Omega +

|

October 9, 2023

View abstract on PubMed

Summary

This study explores using rare-earth doped cadmium sulfide (CdS) as a buffer layer in cadmium telluride (CdTe) solar cells. Doping CdS with samarium (Sm) and lanthanum (La) enhances conductivity and optimizes the bandgap for improved solar cell efficiency.

Area Of Science

Materials Science
Solid State Physics
Photovoltaics

Background

Cadmium sulfide (CdS) is a common buffer layer in CdTe solar cells.
Optimizing buffer layer properties is crucial for enhancing solar cell performance.

Purpose Of The Study

To investigate the viability of rare-earth doped CdS (Sm, La) as a buffer layer in CdTe solar cells.
To analyze the impact of Sm and La doping on the optical, photoluminescence, morphological, and electrical properties of CdS films.
To enhance photoconductivity and optimize the optical bandgap for improved photovoltaic efficiency.

Main Methods

Fabrication of CdS films using a thermal coating technique.
Doping CdS films with samarium (Sm) and lanthanum (La) rare-earth ions.
Characterization using optical microscopy, scanning electron microscopy (SEM), UV-Vis spectroscopy, photoluminescence (PL) spectroscopy, and electrical measurements.

Main Results

Doping with Sm and La resulted in a granular-like structure observed via SEM.
Optical transmission decreased from ~80% to 68% in the visible region.
The optical bandgap was reduced from 2.43 eV to 2.27 eV.
Photoluminescence spectra showed emission peaks in the visible region attributed to band-to-band and band-to-impurity transitions.
Electrical measurements indicated enhanced conductivity due to the reduced bandgap.

Conclusions

Rare-earth doped CdS films exhibit promising properties for use as buffer layers in CdTe solar cells.
The observed enhancement in conductivity and optimized bandgap suggest potential for improved photovoltaic device efficiency.
This research highlights the potential of Sm and La doping to tailor CdS properties for advanced solar energy applications.