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The Synthesis and Characterization of Colloidal Nanocrystals for Perovskite Solar Cells

The Synthesis and Characterization of Colloidal Nanocrystals for Perovskite Solar Cells
Translated Title
효율적인 페로브스카이트 태양 전지를 위한 정공 전달용 콜로이드 나노 입자 개발
Lee, Seung Ho
DGIST Authors
Lee, Seung Ho; Lee, Jong Soo; Jeong, Nak Cheon
Lee, Jong Soo
Jeong, Nak Cheon
Issue Date
Available Date
Degree Date
2016. 8
hot-injection methodPerovskite solar cellsn-i-p heterojunction solar cellcolloidal quantum dotsPbSCZTS QDsCZTSe QDs
In recent times, the emergence of organic-inorganic halide perovskite materials have been considerable attention to many scientists in photovoltaic fields due to high light absorption coefficient, outstanding charge carriers diffusion length and optical band gap as light absorbers. Herein, we have applied colloidal quantum dots to hole-conducting layers in methylammonium lead triiodide-based perovskite solar cells. First, we use lead sulfide(PbS), colloidal quantum dots(QDs) which are synthesized by hot-injection method due to low-cost, solution-processable materials, strong absorption coefficient and size-dependent optical properties compared to expensive organic-conducting materials. They are spin-coated on mesoscopic perovskite layers to form n-i-p junctions. The devices with different optical band gaps of PbS QDs show slightly enhanced current density contrary to reduced open-circuit voltages than hole-free perovskite solar cells. The maximum power conversion efficiency has reached 6.7% with PbS QDs. We also synthesized Au-PbS core-shell structures for the hole-transporting layer due to strong p-type doping effect resulting in enhanced hole transfer and the relation between plasmon from cores and excitons from shells. Furthermore, we have applied CZTS and CZTSe QDs composed of quaternary Copper-Zinc-Tin-Sulfur or Selenium compounds to hole transport layer for enhancing the photovoltaic performances and tuning band gaps of perovskite solar cells. CZTS and CZTSe QDs with diameters of 10 to 20nm were also synthesized by hot-injection method and when they are spin-coated on the absorber layer solar cell devices show higher current density, open-circuit voltage and IPCE than hole-conducting materials free perovskite solar cell. Their maximum power conversion efficiency has been over 7% and open-circuit voltage has been changed depending on particle’s compositions. ⓒ 2016 DGIST
Table Of Contents
1. Introduction 1 -- 2. Theoretical Section 4 -- 2.1. Colloidal Quantum Dots 4 -- 2.1.1. Solution phase synthesis of quantum dot nanoparticles 4 -- 2.1.2. Properties of colloidal quantum dot nanoparticles 4 -- 2.2. Perovskite Solar Cells 5 -- 2.2.1 The advancement of efficiency in perovskite solar cells 5 -- 2.2.2 Properties of organic-inorganic perovskite materials 6 -- 2.2.3 Structural types of perovskite solar cells 7 -- 2.2.4 Fabricating solution-processed perovskite solar cells 8 -- 3. Experimental Section 9 -- 3.1. Materials 9 -- 3.2. Synthesis of Colloidal Quantum Dots 9 -- 3.2.1. Synthesis of colloidal gold nanocrystals 9 -- 3.2.1. Synthesis of colloidal PbS quantum dots 10 -- 3.2.2. Synthesis of colloidal Au-PbS quantum dots 10 -- 3.2.3. Synthesis of colloidal Cu2ZnSnS4 quantum dots 11 -- 3.2.4. Synthesis of colloidal Cu2ZnSnSe4 quantum dots 12 -- 3.3. Solar Cell Fabrication 12 -- 3.4. Characterization 14 -- 4. Results & Discussion 16 -- 4.1. Characterization of colloidal quantum dots 16 -- 4.2. Characterization of perovskite films 22 -- 4.3. Characterization of perovskite solar cells with nanocrystals 27 -- 5. Summary & conclusion 35 -- 6. References 36
Energy Systems Engineering
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