Temperature-dependent thermoelectric and multiband photoresponse of undoped, Co-doped and Co-B co-doped ZnO thin films
MATERIALS RESEARCH EXPRESS, cilt.13, sa.2, 2026 (SCI-Expanded, Scopus)
- Yayın Türü: Makale / Tam Makale
- Cilt numarası: 13 Sayı: 2
- Basım Tarihi: 2026
- Doi Numarası: 10.1088/2053-1591/ae366c
- Dergi Adı: MATERIALS RESEARCH EXPRESS
- Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Chemical Abstracts Core, Compendex, INSPEC, Directory of Open Access Journals
- İstanbul Üniversitesi Adresli: Evet
Özet
This study investigated the thermoelectric and multiband photoresponse characteristics under temperature variation for undoped, Co-doped and Co-B co-doped zinc oxide (ZnO) thin films. The films were successfully synthesized via the sol-gel spray method. The electrical resistance of the samples was measured in the temperature range of 300-500 K under dark, ultraviolet (UV), visible (Vis), and infrared (IR) illumination conditions to determine their photoresponse behavior. The thermoelectric performances of the samples were evaluated in the temperature range of 300-550 K by measuring the Seebeck coefficient and electrical conductivity, followed by calculating the power factor (PF). All films exhibited n-type conductivity with thermally activated transport dominated by defect-assisted hopping. Co doping enhanced carrier activation and introduced shallow donor states, yielding Seebeck coefficients up to -2250 mu V/K (1% Co-doped ZnO). Co-B co-doping further improved electrical conductivity and reduced activation energy to similar to 0.16 eV, resulting in a power factor of 610 mu W.m(-1).K-2 for 2% Co-1% B co-doped ZnO at 500 K. This value is approximately 6000 times greater than that of undoped ZnO. 1% Co-1% B co-doped ZnO sample demonstrated broadband photoresponse with Rp > 90% across UV-Vis-IR spectra, confirming synergistic defect modulation. These findings highlight the potential of Co-B co-doped ZnO films for multifunctional energy harvesting and photodetection applications under variable thermal and optical conditions.