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Synthesis and Characterization of Ternary Metal Chalcogenides for Photovoltaic Applications

Synthesis and Characterization of Ternary Metal Chalcogenides for Photovoltaic Applications
Translated Title
태양전지 응용을 위한 삼원계 금속 칼코게나이드의 합성과 특성
Omar Ramirez Sanchez
DGIST Authors
Sanchez, Omar Ramirez; Lee, Jong SooChoi, Yong Chan
Jong-Soo Lee
Yong Chan Choi
Issue Date
Available Date
Degree Date
2018. 8
Solar cells, chalcogenides, ligand exchange, molecular inks, cation exchange
With the aim to equalize solar energy and the energy production cost of fossil fuels, researchers had turned their efforts towards the development of new generations of solar cells. The synthe-sis of new materials with remarkable characteristics has been a major goal for the research community in order to overcome the limitations that had prevented the solar energy to displace the fossil fuels as our primary source of energy. Several materials are in the spotlight for its promising properties such as perovskites and chalcogenides. Among the available inorganic compounds, Cu-based chalcogenides are especially attractive for photovoltaic applications do to their potential to extend light harvesting into the near infrared region of the solar spectrum, their optical and electrical characteristics and large variety which includes earth-abundant, nontoxic and inexpensive elements. In this work, several routes for the synthesis of copper-antimony-sulfide/selenide compounds are explored such as ligand exchange, where organic fatty ligands that surround the surface of nanocrystals are removed and replaced by shorter inorganic onesmolecular inks, where bulk materials are dissolved in a thiol-amine mixture at low temperatures allowing a complete solution process fabricationand cation exchange, which is a post-synthetic strategy for the fabrication of ionic nanocrystals that allows the total or partial replacement of host cations in the lattice of a pre-synthesized parent system. Herein, the whole process of the solar cell is covered: Synthe-sis, characterization and fabrication. The most remarkable finding in this work is the effect of the volume change (ΔV) in the crystal structure between the parent nanocrystal and the final composition on the morphology of cubic berzelianite Cu2-xSe nanoparticles while inducing partial cation exchange with Ge4+ and Sb3+. We found that in the case of Ge4+(ΔV 11.3%), the nanoparticles’ size and shape remained basi-cally the same, but when CE with Sb3+ was performed, monocrystalline nanoplates of around 200 nm were obtained. We observed that when Sb3+ goes inside the lattice of the Cu2-xSe nano-particles, it triggers a reorganization of the anion framework because of the high stress induced in the lattice. As these metastable nanoparticles gain energy as Sb3+ continues to substitute Cu+ ions, the nanoparticles start to orient and attach as a way to reduce their surface stress and en-ergy, thus forming the nanoplates. This new approach for growing larger crystals can help to overcome the limitations of small nanoparticles and to broaden even further the sea of possibili-ties to synthesize more and more complex materials.
Table Of Contents
Part I. Phase Control Synthesis of Copper Antimony Sulfide Thin Films 1-- INTRODUCTION 2-- EXPERIMENTAL SECTION 4-- RESULTS AND DISCUSSION 6-- Ligand Exchange 6-- Solution processed CuSbS2 10-- CONCLUSIONS 15-- Part II. Synthesis of Cu3SbSe3 and Cu2GeSe3 Nanocrystals via Partial Cation Exchange Reactions 16-- INTRODUCTION 17-- EXPERIMENTAL SECTION 20-- RESULTS AND DISCUSSION 22-- Cation exchange with Ge4+ 22-- Cation exchange with Sb3+ 25-- CONCLUSIONS 40-- REFERENCES 41--
Energy Science and Engineering
Related Researcher
  • Author Lee, Jong-Soo MNEDL(Multifunctional Nanomaterials & Energy Devices Lab)
  • Research Interests Design of new type of multifunctional nanoparticles for energy-related devices; 다기능성 나노재료; 무기물 태양전지; 열전소자
Department of Energy Science and EngineeringThesesMaster

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