RESUMEN
Electrochemistry of surface-bound molecules is of high importance for numerous electronic and sensor applications. Extracting the electron transfer rate is beneficial for understanding surface-bound processes, but it requires experimental or computational rigor. We evaluate methods to determine electron transfer rates from large voltammetry sets from experiments via machine learning using decision tree ensembles, neural networks, and gaussian process regression models. We applied these to reproduce computational measures of electron transfer rates modeled by first principles. The best machine learning models were a random forest with 80 decision trees and a neural network with Bayesian regularization, producing root mean squared errors of 0.37 and 0.49â s-1 , respectively, corresponding to mean percent errors of 0.38 % and 0.52 %, respectively. This work establishes machine learning methods for rapidly acquiring electron transfer rates across large datasets for widespread applications.
RESUMEN
Van der Waals heterostructures consisting of two-dimensional materials offer a platform to obtain materials by design and are very attractive owing to unique electronic states. Research on 2D van der Waals heterostructures (vdWH) has so far been focused on fabricating individually stacked atomically thin unary or binary crystals. Such systems include graphene, hexagonal boron nitride, and members of the transition metal dichalcogenide family. Here we present our experimental study of the optoelectronic properties of a naturally occurring vdWH, known as franckeite, which is a complex layered crystal composed of lead, tin, antimony, iron, and sulfur. We present here that thin film franckeite (60 nm < d < 100 nm) behaves as a narrow band gap semiconductor demonstrating a wide-band photoresponse. We have observed the band-edge transition at â¼1500 nm (â¼830 meV) and high external quantum efficiency (EQE ≈ 3%) at room temperature. Laser-power-resolved and temperature-resolved photocurrent measurements reveal that the photocarrier generation and recombination are dominated by continuously distributed trap states within the band gap. To understand wavelength-resolved photocurrent, we also calculated the optical absorption properties via density functional theory. Finally, we have shown that the device has a fast photoresponse with a rise time as fast as â¼1 ms. Our study provides a fundamental understanding of the optoelectronic behavior in a complex naturally occurring vdWH, and may pave an avenue toward developing nanoscale optoelectronic devices with tailored properties.
