In a recent study, researchers at the National Nanotechnology Laboratory (NNL)-CNR Istituto di Nanoscienze have examined the use of dilute carboxylic acid solutions on heterostructured CdSe@CdTe tetrapods to promote more effective inter-particle charge transfer and improve the photovoltaic performance of tetrapod-based solar cells.

Treatments with acetic and trifluoroacetic acids on CdSe@CdTe tetrapod solids led to a doubled photovoltaic performance when compared with the standard pyridine exchange procedure.

Through a complete characterization of the treated NC solids (FTIR spectroscopy, AFM inspection and transport measurements) the team showed that the improved photovoltaic performance can be attributed to a complete removal of the insulating organic ligand from the NC surface, which results in better electronic coupling, and optimizes the morphology of the material.

Suits flexible substrates

Post-deposition treatment with carboxylic acids represents an effective low-temperature method to electronically couple CdSe@CdTe-shaped tetrapods for photovoltaic applications. This relatively gentle technique improves charge transport across multiple tetrapods to create pathways for carriers, without disrupting the chemical structure of the NCs and other components of the device.

According to the team, the method is fully compatible with plastic and flexible polymeric device technology.

Full details can be found in the journal Nanotechnology.