First-principles study on fundamental optoelectronic properties and surface characteristics of I-V-VI2 ternary compounds
Yeunhee Lee a, Dongsuk Yoo b, Yong-Hyun Kim a b
a Korea Advanced Institute of Science and Technology (KAIST), South Korea, Korea, Republic of
b Korea Advanced Institute of Science and Technology (KAIST), South Korea, Korea, Republic of
nanoGe Fall Meeting
Proceedings of nanoGe Fall Meeting19 (NGFM19)
#NCFun19. Fundamental Processes in Semiconductor Nanocrystals
Berlin, Germany, 2019 November 3rd - 8th
Organizers: Ivan Infante and Jonathan Owen
Poster, Yeunhee Lee, 410
Publication date: 18th July 2019

Monodisperse semiconductor nanocrystals (NCs) have been widely applied to optoelectronic devices such as photovoltaic (PV) cells and light-emitting diodes (LEDs). Recently, Ag-based ternary chalcogenide semiconductors have attracted attention as a new material class because they have several advantages of suitable band gaps, high absorption coefficients, and more importantly earth-abundant and eco-friendly constituent elements. In 2016, Konstantatos et al. succeeded in synthesizing AgBiS2 NCs with 6.3% power conversion efficiencies (PCEs) in PV without hysteresis1. Because their crystal structure is more complicated to synthesize than that of binary compounds, many combinations of ternary materials have not yet been pioneered. Also, surface characteristics of Ag-based ternary chalcogenide NCs have not been understood clearly yet.

In this work, we have analyzed physical properties of bulk I-V-VI2 ternary chalcogenide compounds depending on specific compositions and also studied shape change of NCs depending on the stability of each surface based on first-principles electronic structure calculations. For bulk, we have found that the monovalent metal (I) has a major influence on the change of optoelectronic properties such as effective mass, exciton binding energy, and exciton Bohr radius. Furthermore, we have analyzed the surface characteristics of LiBiS2 and AgBiS2, theoretically identified as excellent candidates for light absorbers, and proposed a possible shape variation of NCs. Our results will guide how to efficiently design and synthesize ternary chalcogenide NCs to be good light absorbers.

 

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