NOVEL VAN DER WAALS HETEROSTRUCTURES: SYNTHESIS, CHARACTERIZATION, AND APPLICATIONS

Author

• Join Uddin, Michigan Technological UniversityFollow

Date of Award

2026

Document Type

Campus Access Dissertation

Degree Name

Doctor of Philosophy in Applied Physics (PhD)

Administrative Home Department

Department of Physics

Advisor 1

Yoke Khin Yap

Committee Member 1

Ranjit Pati

Committee Member 2

John A. Jaszczak

Committee Member 3

Paul Bergstrom

Abstract

Two-dimensional (2D) materials have attracted widespread research interest owing to their exceptional electrical and optical properties, enabling improved performance across diverse applications. These materials have enabled the development of solar cells based on 2D van der Waals (vdW) nanostructures. Recently, we discovered a new class of quantum dots (QDs) (we called DMA-CO) that emit ultraviolet-visible (UV-Vis) light and are non-toxic. Unlike traditional inorganic QDs, which are crystalline, DMA-COs are likely molecular clusters; therefore, new methods are needed to form core-shell structures. This work proposed two methods for forming vdW core-shell quantum dots (CSQDs) with DMA-CO cores. We studied two types of vdW CSQDs: stacked vdW CSQDs and thin-film vdW CSQDs. We used hexagonal boron nitride (h-BN) and molybdenum disulfide (MoS₂) as the shell materials. Solar cells (SCs) based on stacked vdW BN/DMA-CO and MoS₂/DMA-CO CSQDs exhibited the highest power conversion efficiencies (PCEs) of 3.63% and 2.07 %, respectively. In addition, SCs based on thin-film vdW MoS₂/DMA-CO CSQD achieved a maximum efficiency of 2.62 %. In contrast, solar cells using stacked DMA-CO QDs and thin-film vdW BN/DMA-CO CSQDs exhibited negligible or no PCE. The measurable PCE observed in both types of solar cells is attributed to the built-in potential, which enables quantum tunneling and reduces trap states. We further outlined directions for improving SC performance based on stacked vdW CSQDs by quantifying the amounts of shell and core materials used. For example, BN dots were used as the shell, and we quantified them using a calibration curve based on UV-Vis spectroscopy.

Recommended Citation

Uddin, Join, "NOVEL VAN DER WAALS HETEROSTRUCTURES: SYNTHESIS, CHARACTERIZATION, AND APPLICATIONS", Campus Access Dissertation, Michigan Technological University, 2026.

https://digitalcommons.mtu.edu/etdr/2142