Communication Dans Un Congrès Année : 2024

Compositional engineering of highly emissive and widely tunable I-III-VI based quantum dots (QDs) for photovoltaic applications

Résumé

In quantum dot sensitized solar cells (QDSSCs), replacing heavy metal based binary II-VI QDs such as Pb (S, Se or Te) or Cd (Se or Te) with I-III-VI counterparts is of high interest for environmental considerations while ensuring optimal device performance. Their ability to get assembled as nanocrystals on the surface of TiO2 with tunable electronic properties through size, shape, and composition makes them worthy light-harvesting material in QDSSCs . In this context, it becomes imperative to extensively investigate the chemical pathways, composition and structure of Cu-In-Zn-Se QDs to achieve competitive photovoltaic characteristics [1]. The present study reports a robust, quick and inexpensive microwave assisted aqueous phase-based approach to produce Cd-free, bright, and highly emissive alloyed Cu-In-Zn-Se/ZnS QDs of small size (~ 2.2 nm). The prepared nanocrystals show widely tunable photoluminescence (PL) emission from 618 to 765 nm by varying feed molar ratio of precursors. Being in line with the systematic PL tunability, their energy gap could be enlarged from 1.73 to 2.12 eV. By leveraging the off-stochiometric effect on PL, QDs having Zn:Cu molar ratio of 1:2 recorded the longest mean decay PL lifetime of 0.63 µs with highest PLQY of 54%. Further, the purified QDs were characterized with UV-visible, PL spectroscopy, FT-IR in combination with XRD and HR-TEM analysis to investigate the role of cation deficiency on their structure. Different strategies were attempted to grow homogenous and crack-free thin films of QDs onto FTO substate to realize QDs-sensitized electrode. Dip coating of Cu-In-Zn-Se/ZnS QDs onto the magnetron sputtered TiO2/FTO substrate resulted in the fabrication of desired QDs-sensitized electrode. Techniques like SEM, DRS and profilometry were extensively employed to monitor the thickness and surface of the fabricated electrode. Photoelectrochemical measurements on tailored QDs-sensitized electrode were conducted. Steady-state current response and dynamic response of the heterostructured QDs/TiO2/FTO system to intermittent illumination was studied by chopped light chronoamperometry. Mott-Schottky analysis was utilized to understand their doping type and energy band alignment of QDs by measuring their flat-band potential. The presence of a small and tight semi-circular shape of Nyquist plot in comparison to unsensitized TiO2 film electrode indicated an improved charge transfer with minimal interfacial effects. The study demonstrates high application prospect of Cu-In-Zn-Se/ZnS QDs sensitized TiO2 thin film electrodes as potential heterostructures in QDSSCs.

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Dates et versions

hal-04612342 , version 1 (14-06-2024)

Identifiants

  • HAL Id : hal-04612342 , version 1

Citer

Shubham Shishodia, Raphaël Schneider, Thomas Gries. Compositional engineering of highly emissive and widely tunable I-III-VI based quantum dots (QDs) for photovoltaic applications. E-MRS 2024 Spring Meeting, European Materials Research Society, May 2024, Strasbourg, France. ⟨hal-04612342⟩
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