Multiple exciton generation in MoS2 nanostructures: A density functional theory study

• Main Authors: Saifful Kamaluddin, Muzakir, Nur Hidayati Ain Natasha, Makimin, Nur Farha, Shaafi, Ruziana, Mohamed, Muhammad Zamzuri, Abdul Kadir
• Format: Book Chapter
• Language: English; English; English
• Published: Springer Nature Singapore Pte Ltd 2024
• Subjects: QC Physics; QD Chemistry
• Online Access: http://umpir.ump.edu.my/id/eprint/40964/1/S%20K%20Muzakir%202024%201.pdf; http://umpir.ump.edu.my/id/eprint/40964/7/Multiple%20exciton%20generation%20in%20MoS2%20nanostructures.pdf; http://umpir.ump.edu.my/id/eprint/40964/8/Intelligent%20Manufacturing%20and%20Mechatronics.pdf; http://umpir.ump.edu.my/id/eprint/40964/; https://doi.org/10.1007/978-981-99-9848-7_36
• Institution: Universiti Malaysia Pahang Al-Sultan Abdullah

Excitonic solar cell which fabricated using quantum confined semiconducting material that exhibits multiple exciton generation (MEG) is speculated could achieve theoretical photovoltaic conversion efficiency more than 60%. However, the expected efficiency has yet to be reached to date. Specific size and morphology of a quantum confined semiconducting material needs to be studied to determine the presence of MEG. The objective of this study is to verify the occurrence of MEG in few realistic cluster models of MoS2 using density functional theory (DFT) calculations. Small MoS2 nanocrystals were modelled using GaussView 5.0 software, which later validated as realistic using harmonic frequency calculations analysis executed by Gaussian 09W software. The presence of MEG in realistic models of MoS2 nanocrystals was studied using time-dependent density functional theory (TD-DFT) calculations. The output of the work is summarized as the followings, (i) (MoS2)n with n = 2, 4, 6, 8 and 12 models were established as realistic, (ii) the size of the nanocrystal models are smaller than its exciton Bohr radius (ca. 1.61 nm) i.e., 0.54, 0.62, 0.95, 1.09 and 1.57 nm respectively, and (iii) all calculated MoS2 nanoparticle models exhibit MEG. Therefore, a practical technique that could synthesize MoS2 nanocrystals with similar structure or geometry with that of the evaluated models would materialize a device with practical photovoltaic conversion efficiency more than 60%.