Organic-Inorganic Semiconductors Demonstrate Enhanced Charge Transfer
© 2023 LIMNO/EPFL
EPFL scientists have made significant progress in the development of hybrid layered organic-inorganic perovskite semiconductors by incorporating novel spacer cations, according to a recent scientific paper published in the journal Chem. Sci. This advance gives promise to addressing the strong dielectric and quantum confinement effects typically encountered in layered perovskite materials, allowing for improved charge-transfer capabilities.
The research results, led by Simon Nussbaum of the LIMNO lab, focused on synthesizing and characterizing thin films of an emerging class of organic-inorganic perovskite semiconductors known as Dion-Jacobson (DJ)-phase materials. These materials feature layered structures in which organic spacer cations are introduced yielding novel optoelectronic properties. In this study, the researchers utilized a spacer cation based on naphthalene diimide (NDI) as the divalent organic molecule for the first time, and investigated its ability to accept photogenerated electrons from the inorganic layer. The scientists synthesized thin films of the NDI-based perovskite semiconductor with varying alkyl chain lengths, ultimately discovering the most promising results with an alkyl chain length of 6 carbons.
Remarkably, the NDI-based thin film exhibited an impressive charge carrier mobility of up to 0.03 cm2 V−1 s−1, as determined by space charge-limited current measurements for quasi-layered thin films when an average layer number of 5 was used. This high charge carrier mobility suggests that the NDI spacer cation effectively mitigates the formation of trap states within the material, leading to enhanced charge transport characteristics. Indeed, the absence of an observable trap-filling region further indicates that the NDI spacer cation serves as an effective passivation agent for trapping sites within the perovskite structure. While further research is needed to optimize the performance of these new perovskite materials, this study marks a critical step forward in harnessing the potential of organic-inorganic hybrid structures for advanced optoelectronic applications and the fabrication of more efficient and stable perovskite-based devices, such as solar cells, light-emitting diodes (LEDs), and photodetectors.