Ternary alloyed CdS1-xSex quantum dots on TiO2/ZnS electrodes for quantum dots-sensitized solar cells

Ternary alloyed and tunable band CdS(1-x)Sex quantum dots (QDs) were prepared via successive ionic layer absorption and reaction (SILAR) method. The as-prepared photoanodes at different concentrations were characterized for structural, surface morphological, optical and electrical analysis. The result indicated that the photoresponse region and energy band of prepared CdS(1-x)SexQDs could be varied by controlling the ratios of S and Se. An aqueous solution of polysulfide electrolyte acted as redox mediator. The QDs size were varied from 10.14 nm to 3.362 nm confirms the quantum confinement effect. The highest and lowest photo conversion efficiency (eta) of TiO2/ZnS/CdS1-xSex/ZnS quantum dots-sensitized solar cells (QDSSCs) using CuS counter electrode was obtained 5.12% and 3.43%, respectively. Developing the ZnS layer between the TiO2/QDs and at the interface of QD/electrolyte helps to suppress the charge recombination rate and provide the potential barrier between QDs and electrolyte.The photoconversion efficiency was evaluated by using a solar simulator under illumination with an AM 1.5 G spectrum having light intensity of 100 mWcm(-2). These results are encouraging and reveals that tunable energy band QDs controlled by the ratio of atoms can contribute an effective approach for developing the higher efficiency of QDSSCs.(c) 2021 Elsevier B.V. All rights reserved.

Automated summary

The tunable band CdS(1-x)Sex quantum dots prepared through controlling the ratios of S and Se exhibited variable photoresponse region and energy band. Addition of a ZnS layer helped suppress recombination rate and improve the efficiency of QDSSCs. The highest efficiency of TiO2/ZnS/CdS1-xSex/ZnS quantum dots-sensitized solar cells with CuS counter electrode reached 5.12%.