CsPbBr3 나노결정 후처리를 통한 광특성 향상 = Enhancement in optical properties of the CsPbBr3 nanocrystals via post-treatment

다국어 초록 (Multilingual Abstract)

Perovskite nanocrystals （NCs） are crystal structure with the ABX3 composition, exhibit enhanced optical performance arising from quantum confinement effects. In paric lar, the tunability of their emission wavelength through halide ion exchange and precise size control enables versatile color modulation across the visible spectrum. Owing to these unique features, perovskite nanocrystals have been widely explored for various optoelectronic applications, including light-emmiting diodes, lasers, and photodetectors. However, they suffer from the degradation of photoluminescence characteristic and the low stability due to their ionic characteristics and the surface defects.
Some studies focus on doping and shelling to address this issue, however, these approaches often involve complex and demaning experimental procedures, requiring precise control over reaction conditions and sophisticated syntheis techniques. While, post-treatment method is gaining their popularity due to their simple but effective surface passivation. In this work, I synthesized the green-emitting CsPbBr3 perovskite NCs using representative room-temperature synthesis method, ligand-assisted reprecipitation method. Subsequently, the synthesized CsPbBr3 NCs are post-treated with oleylamine and the ZnBr2 salt, respectively, to enhance their optical properties. The optical properties of the resulitng NC solutions are examined using absorption and photoluminescence（PL） spectroscopy, and PL quantum yield.
Furthermore, their structural properties are investigated using transmit electron microscopy. The correlation between the actual size and the optical properties is examined using the Tauc plot and effective mass approximation. Lastly, the carrier dynamics and the passivation mechanism were investigated using time-resolved PL, which is a
powerful tool to observe the carrier recombination time of the luminescent material.

목차 (Table of Contents)

• 1. 서론 1
• 2. 이론적 배경 3
• 2. 1 양자구속효과 3
• 2. 2 콜로이드 나노결정 7
• 2. 3 페로브스카이트 나노결정의 표면 결함 및 부동태화 9
• 3. 페로브스카이트 나노결정 합성 및 측정 방법 12
• 3. 1 페로브스카이트 나노결정 합성 방법 12
• 3. 1. 1 리간드 보조 재침전법(LARP) 12
• 3. 1. 2 나노결정 후처리 방법 14
• 3. 2 측정 16
• 3. 2. 1 흡수 (Absorption) 16
• 3. 2. 2 광 발광 (Photoluminescence) 20
• 3. 2. 3 Cs corrected-field emission transmission electron microscopy (Cs-TEM) 측정 22
• 3. 2. 4 운반자 동역학 (Carrier dynamics) 24
• 4. 측정 결과 및 분석 27
• 4. 1 OAm 첨가실험 측정 결과 및 분석 27
• 4. 1. 1 흡수 특성 분석 27
• 4. 1. 2 발광 특성 분석 28
• 4. 1. 3 Tauc plot과 Effective mass approximation을 이용한 크기 계산 34
• 4. 1. 4 구조 특성 분석 36
• 4. 1. 5 운반자 동역학 분석 43
• 4. 2 ZnBr2 첨가실험 측정 결과 및 분석 48
• 4. 2. 1 흡수 특성 분석 48
• 4. 2. 2 발광 특성 분석 49
• 4. 2. 3 구조 특성 분석 54
• 4. 2. 4 운반자 동역학 분석 64
• 5. 결론 70
• 6. 참고문헌 72