Improving the performance of CdTe QDSSCs by chloride treatment and parameter optimization

Abstract

In this study, organometallic CdTe(Cl) Quantum Dot Sensitized Solar Cells (QDSSCs) using cadmium chloride (CdCl2) treated CdTe QDs were designed for the first time in the literature. The study is divided into 3 basic sections; synthesis of CdTe QD, treatment of CdTe QD with CdCl2 and design CdTe(Cl) QDSSCs. The hot injection method modified by Cannula method was used to synthesize organometallic CdTe QDs. The chloride passivation procedure was applied to CdTe QD with injection of different amount of chloride (12–96 CdCl2/nm2) into the CdTe solution. Uv–vis, Photoluminescence (PL), PL Quantum Yield (PLQY), Full width Half Maximum (FWHM) analyses were performed for all CdTe QDs which were synthesized and treated with chloride. As a result of the analyses, PLQY value was increased from 25.66 ± 2.1 to 87.33 ± 2.1% with 60 CdCl2/nm2 treatment. To determine the effects of chloride treatment on QDSSC, CdTe QDSSCs were designed using 6 different CdTe (CI) QDs obtained by different amounts of chloride treatments applied to the surfaces of CdTe QDs. After that, TiO2 thickness, collector electrode selection were chosen by experimental optimization. As a result of the study, FTO/TiCl4/TiO2 (22 µm)/TiCl4/(36 CdCl2/nm2) CdTe(Cl) QD surface was used as the photo anode at the end of all optimization procedures, while FTO/Pt was selected as the collecting electrode surface. I-/I3- redox pairs were injected between these two surfaces. For the designed QDSSC, Jsc, Voc, filling factor (FF), Power Conversion Efficiency (PCE) were found 2.842 ± 0.10 mA/cm2, 0.810 ± 0.019 V, 56.630 ± 1.79%, 1.306 ± 0.10% respectively. This efficiency value is 5.58 times better than the most efficient CdTe QDSSC's efficiency (0.234%) obtained by using organometallic CdTe QDs in the literature.