Tunable Optoelectronic and Thermoelectric Properties of Ag/Ga-Doped PbS Surfaces: A DFT Study on Doping and Surface Engineering
Muhammad Jawad1, Muhammad Mudassir Ahmad Alwi2,*, Akbar Niaz2, Monaf Hodhod3, Noor ul Amin4, Fiaz Hussain5,*
1 Faculty of Science Education, Jeju National University, Jeju, Republic of Korea
2 Department of Materials Engineering, College of Engineering, King Faisal University, Al-Hofuf, Al-Ahsa, Saudi Arabia
3 Department of Mechanical Engineering, College of Engineering, King Faisal University, Al-Hofuf, Al-Ahsa, Saudi Arabia
4 Department of Chemistry, Abdul Wali Khan University Mardan, Mardan, Pakistan
5 Department of Mechanical Engineering, Gachon University, Seongnam-si, Gyeonggi-do, Republic of Korea
* Corresponding Author: Muhammad Mudassir Ahmad Alwi. Email: 
; Fiaz Hussain. Email: 
Computers, Materials & Continua https://doi.org/10.32604/cmc.2026.079905
Received 30 January 2026; Accepted 13 May 2026; Published online 22 May 2026
Abstract
Lead sulfide (PbS) is a narrow bandgap IV–VI semiconductor with important applications in infrared optoelectronics and thermoelectric energy conversion. Surface engineering and controlled doping provide effective strategies for tuning its electronic and optical properties. In this work, the structural, electronic, optical, and thermoelectric properties of bulk PbS, pristine PbS (110) surfaces, and Ga- and Ag-doped PbS (110) surfaces are systematically investigated using density functional theory within the full-potential linearized augmented plane wave framework. The calculated lattice constant of bulk PbS is 5.88 Å, which agrees well with experimental data. Electronic structure calculations show that bulk PbS exhibits a direct bandgap of 0.75 eV at the L point. The pristine PbS (110) surface shows an enlarged bandgap of 1.07 eV due to surface quantum confinement. Surface doping strongly modifies the electronic structure. Ag doping increases the bandgap to 1.24 eV through donor-like states, whereas Ga doping slightly reduces it to 1.01 eV by introducing acceptor states near the valence band. These electronic modifications lead to significant changes in optical behavior, including enhanced absorption in the visible and near-infrared regions and tunable dielectric response. Thermoelectric analysis reveals that the pristine surface exhibits a high power factor of approximately 4.0 × 10
11 W/m·K
2 at 300 K, while bulk PbS reaches a maximum value of 4.7 × 10
11 W/m·K
2 at 800 K. These results demonstrate that dopant-induced band modulation and surface engineering provide an effective approach for tuning the optoelectronic and thermoelectric performance of PbS-based nanostructures for advanced energy and photonic applications.
Keywords
PbS surface; optoelectronic properties; Ga and Ag doping; DFT; thermoelectric properties
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