Highly efficient and durable electron transport layer for QDSSC: An integrated approach to address recombination losses

Highlights: • Nd³⁺ incorporation to enhance the light absorption, induce defects and improve charge separation. • 1D Graphene nanoribbons incorporated electron transport layer for quick electron extraction. • Hybrid photoanode with Nd-TiO₂ and GNR composite as electron transport material. • Enhancement of PCE to 5.8% compared to 2.69% for TiO_2. -- Abstract: Quantum dot sensitized solar cells (QDSSC) are up-and-coming low cost third-generation solar cells technology. The distinctive properties of quantum dots (QDs) feature QDSSC as an optimistic future of photovoltaics. The real concern with these devices is the wide band gap semiconductors used as the electron transport layer. Electron transport layers in quantum dot sensitized solar cells suffer from performance losses arising from recombination of electrons. This work tries to entail an integrated approach of tailoring the nanostructure as an exclusive electron transport layer to overcome the recombination losses. We adopted doping of Neodymium into TiO₂ (Nd-TiO₂) to create intermittent band gap states that can extend the charge carrier lifetime and rendered the defect material (Nd-TiO₂) as a hybrid composite with 1D Graphene nanoribbons for quick electron extraction. This approach carefully alters ETL's functionality, and its utility has emerged into a potential electrode for QDSSC. Our tailored photoanode reports a higher efficiency of ~ 6% for cadmium sulfide QDs deposited via successive ionic layer adsorption and reaction (SILAR) and stands as highly efficient photoanode for QDSSC. This opens a clear channel in the realm of applications like photocatalysis, photovoltaics, and energy devices that involve metal oxide nanostructures for efficient charge separation.