Efficient counter electrode for quantum dot sensitized solar cells using p-type PbS@reduced graphene oxide composite

Area of Science:

• Materials Science
• Renewable Energy
• Nanotechnology

Background:

• Quantum dot-sensitized solar cells (QDSSCs) require efficient counter electrodes for optimal performance.
• Traditional counter electrodes often face limitations in charge transport and catalytic activity.
• Graphene-based composites offer promising solutions for enhancing solar cell efficiency.

Purpose of the Study:

• To develop a novel lead sulfide-reduced graphene oxide (PbS-rGO) composite counter electrode.
• To investigate the impact of varying rGO content on the performance of PbS-rGO composites in QDSSCs.
• To enhance the power conversion efficiency (PCE) and electrochemical properties of QDSSCs.

Main Methods:

• Synthesis of PbS-rGO composite via a hydrothermal method, anchoring PbS nanocubes onto reduced graphene oxide (rGO) sheets.
• Fabrication of QDSSCs utilizing the synthesized PbS-rGO composite as the counter electrode.
• Electrochemical characterization, including cyclic voltammetry and electrochemical impedance spectroscopy, to evaluate catalytic activity and charge transfer resistance.

Main Results:

• The optimized rGO-PbS (0.03) composite achieved a high power conversion efficiency (PCE) of 5.358%.
• The composite exhibited improved open-circuit voltage (V_oc) of 0.540 V, short-circuit current density (J_sc) of 21.157 mA cm^-2, and fill factor (FF) of 0.516.
• Electrochemical analyses confirmed superior electrocatalytic activity for the S^2-/S₂^2- redox couple and reduced charge transfer resistance.

Conclusions:

• The PbS-rGO composite serves as a highly effective counter electrode for QDSSCs, surpassing the performance of electrodes without rGO.
• The interconnected rGO framework enhances charge transport, reduces resistance, and improves overall conductivity.
• The hierarchical structure and optimized band alignment contribute to efficient charge transfer and light absorption, leading to enhanced solar cell performance.