The Impact of N-Doped Carbon Quantum Dots on Dye-Sensitized Solar Cells Operating Under Diffused- and Low-Light Intensity

This study investigates the double role of N-doped carbon quantum dots (N-CQDs) in dye-sensitized solar cells (DSSCs) that operate under diffused- and low-light intensity conditions. We demonstrate that the incorporation of N-CQDs leads to a substantial improvement in the performance of DSSCs. Under standard one-sun illumination, the maximum power conversion efficiency (PCE) achieved with N-CQDs is 2% higher than that of the bare cell. Moreover, we introduce two new metrics, the diffused-light coefficient and the low-light intensity coefficient, to evaluate the performance of DSSCs under nonideal illumination conditions. The diffused-light coefficient is recorded at 1.55, which indicates a notable enhancement in diffused-light PCE with N-CQDs. In contrast, the low-light intensity coefficient shows a significant enhancement factor 2, which highlights the superior performance of N-CQD-based DSSCs under low-light conditions. Our findings demonstrate that N-CQDs play a dual role in DSSCs, by being added to both the commercial dye and the mesoporous TiO
₂
layer. These results provide valuable insights to develop and optimize DSSCs, especially for applications in indoor or low-light environments. The proposed metrics, the diffused light coefficient, and the low-light intensity coefficient, offer a meaningful assessment of the device's performance under nonideal illumination conditions.