Synergistic enhancement of photogenerated charge transfer: tailoring optical and electrical properties of PbS:rGO solution processed hybrids

Abstract

Nanostructured materials have significantly influenced numerous scientific and technological areas, mainly due to the tuneability of their optical and electrical properties. When working with quantum dots (QDs)-based thin films, the high prevalence of trap states and low conductivity has been a remarkable challenge, which has been addressed by the fabrication of hybrid materials. However, on the road to improving their properties, fabrication of nanostructured hybrid materials, especially when involving 2D nanomaterials, still poses a challenging task, particularly when solution-processed approaches are considered. In the current work, the fabrication of a solution-processed QDs-2D nanomaterial hybrid, comprising PbS QDs and thermally reduced graphene oxide (rGO) is discussed. This study explores the nanostructured hybrid material's behavior when varying the weight percent ratio between the constituents, revealing a substantial impact of this parameter on the optoelectronic properties of the resulting hybrid material; particularly affecting the photogenerated charge carrier transfer, charge carrier mobility, charge carrier concentration and resistivity. Physical characterization of the hybrid material revealed a dramatic change in the interaction between the PbS QDs and the rGO as the weight percent of rGO increased in the hybrid material, showing a clear reduction of PbS QDs coverage on rGO’s surface, which also produced an increment in the signals related to the oxidation of PbS QDs and rGO. The sample with 5% wt. of rGO showed optimal optoelectronic properties for possible applications in photodetector technologies or solar cells, displaying a high photogenerated current with a charge carrier mobility, charge carrier concentration, and resistivity of approximately 2.26 cm²/V-s, 1.27 × 10¹⁴ cm⁻³ and 2.18 × 10⁴ Ω-cm, respectively. These findings serve as a foundational basis for the development of efficient optoelectronic devices based on this type of nanostructured hybrid material.