S/Mo ratio and petal size controlled MoS₂ nanoflowers with low temperature metal organic chemical vapor deposition and their application in solar cells

Abstract

Vertically aligned two-dimensional (2D) molybdenum disulfide nanoflowers (MoS2 NFs) have drawn considerable attention as a novel functional material with potential for next-generation applications owing to their inherently distinctive structure and extraordinary properties. We report a simple metal organic chemical vapor deposition (MOCVD) method that can grow high crystal quality, large-scale and highly homogeneous MoS2 NFs through precisely controlling the partial pressure ratio of H2S reaction gas, P SR, to Mo(CO)6 precursor, P MoP, at a substrate temperature of 250 °C. We investigate microscopically and spectroscopically that the S/Mo ratio, optical properties and orientation of the grown MoS2 NFs can be controlled by adjusting the partial pressure ratio, P SR/P MoP. It is also shown that the low temperature MOCVD (LT-MOCVD) growth method can regulate the petal size of MoS2 NFs through the growth time, thereby controlling photoluminescence intensity. More importantly, the MoS2 NFs/GaAs heterojunction flexible solar cell exhibiting a power conversion efficiency of ∼1.3% under air mass 1.5 G illumination demonstrates the utility of the LT-MOCVD method that enables the direct growth of MoS2 NFs on the flexible devices. Our work can pave the way for practical, easy-to-fabricate 2D materials integrated flexible devices in optical and photonic applications.

Effect of Measurement System Configuration and Operating Conditions on 2D Material-Based Gas Sensor Sensitivity

“…For the fabrication of the gas sensor based on MoS 2 nanoflower, the MoS 2 , an active sensing layer, was grown on a p-type Si wafer with 300-nm-thick SiO 2 (1–10 Ω·cm, iTASCO, Seoul, Korea) using metalorganic chemical vapor deposition (MOCVD) at a partial pressure ratio of 1.9 in the H 2 S to the Mo(CO) 6 precursor [ 35 ]. Figure S1 (Supplementary Materials) shows the scanning electron microscopy (SEM) image of the MoS 2 nanoflower sample, which is a sensing material of the gas sensor.…”