Elaheh K. Goharshadi

This study presents a systematic investigation into the structural, optical, and photovoltaic properties of pristine and Ba-doped VO2 (VO2-Bax, x = 1, 3, and 5 wt %) nanoparticles and their influence on the performance of perovskite solar cells (PSCs). Among all samples, VO2-Ba3 exhibited the highest visible-light absorption with a band gap reduction from 2.77 eV (VO2) to 2.46 eV. Upon incorporation into the mesoporous TiO2 (m-TiO2) layer, VO2-Ba3 led to a red shift in the absorption edge (389.77 nm), band gap narrowing to 3.18 eV, and improved surface roughness (Ra = 43.20 nm, Rq = 54.32 nm). Perovskite films deposited on VO2-Ba3-modified m-TiO2 displayed enhanced crystallinity, larger grain size (173.19 nm), reduced defect density, and a reduced band gap (1.92 eV vs 2.15 eV for pristine). Devices with the architecture FTO/c-TiO2/m-TiO2 + VO2-Ba3/MAPbI3/spiro-OMeTAD/Ag achieved the highest power conversion efficiency of 7.13%, with a VOC of 0.77 V, a JSC of 17.15 mA cm–2, and a fill factor of 0.54─representing a 41% increase in efficiency compared to the control (5.04%). External quantum efficiency enhancement in the 430–800 nm range, combined with lower Rct and Rs values, confirms VO2-Ba3 as a promising dopant for electron transport layer in high-performance PSCs. All photovoltaic measurements were independently repeated on multiple devices, and the reported values represent reproducible device performance.

Luminescent solar concentrators (LSCs) utilizing carbon dots (CDs) have emerged as promising solutions for transparent photovoltaic applications due to their high transparency and efficient light-to-electricity conversion. This study investigates the synthesis and optical enhancement of CDs doped with transition metal ions—cobalt, nickel, copper, and zinc—to improve LSC performance. Using a microwave synthesis method, we produced CDs with a high quantum yield of 81%, a substantial Stokes shift of 0.71 eV, and excellent stability. Doping CDs with metal ions at molar concentrations of 1%, 3%, and 5% revealed that 1 mol% copper-doped CDs exhibited superior optical properties, enhancing light absorption and emission through effective metal-ion interactions. LSCs, fabricated with dimensions of 15 × 15 × 0.6 cm³ using glass and PMMA waveguides, achieved notable photovoltaic performance with an optical efficiency of 3.99% and a photoconversion efficiency (PCE) of 1.45% for PMMA-based devices. The introduction of copper at 1% concentration resulted in a 22% increase in both optical efficiency and PCE. Stability assessments over 90 days indicated minimal performance degradation, underscoring the robustness of the synthesized materials. This research highlights the potential of metal-doped CDs to optimize LSC technology, facilitating integration into urban environments and advancing the commercialization of transparent photovoltaic systems.