Infrared radiation accounts for approximately 50% of the solar spectrum. Specifically, the near-infrared (NIR) spectrum, ranging from 760 nm to 2500 nm, is primarily responsible for solar heat gain, increasing indoor temperatures and reducing heating and cooling efficiency. To address this issue, we developed a highly transparent thermo-shielding flexible film that maintains a high transmittance of the visible region (T = 80%) while reducing the transmittance of the NIR region (T ≈ 0%). NIR-absorbing indium tin oxide (ITO) nanocrystals were coated onto polyethylene terephthalate (PET) films, and both films were sandwiched to improve the NIR absorption properties and protect the nanocrystal film layer. The fabricated films were applied to a model house and decreased the indoor temperature by approximately 8°C. Our study demonstrates that energy consumption can be reduced by ITO nanocrystal-coated flexible films, with potential implications for the smart window and mobility markets.

1. Introduction 
2. Experimental 
3. Results and Discussion 
    3.1. Tin 도핑 농도에 따른 콜로이드 ITO 반도체 나노입자의 특성 
    3.2. 콜로이드 ITO 반도체 나노입자가 코팅된 단일 및 이중 필름 비교 
    3.3. 모델 하우스 적용을 통한 나노입자 유연 필름 열 차단 성능 평가 
4. Conclusion 
Funding
Conflict of Interest  
Author Information and Contribution 
Acknowledgement
References

• 배효인(서울과학기술대학교 화공생명공학과) | Hyoin Bae (Department of Chemical and Biomolecular Engineering, Seoul National University of Science & Technology, Seoul 01811, Republic of Korea)
• 정혜연(서울과학기술대학교 화공생명공학과) | Hyeyeon Jung (Department of Chemical and Biomolecular Engineering, Seoul National University of Science & Technology, Seoul 01811, Republic of Korea)
• 이주나(서울과학기술대학교 화공생명공학과) | Juna Lee (Department of Chemical and Biomolecular Engineering, Seoul National University of Science & Technology, Seoul 01811, Republic of Korea)
• 허성연(서울과학기술대학교 화공생명공학과) | Sungyeon Heo (Department of Chemical and Biomolecular Engineering, Seoul National University of Science & Technology, Seoul 01811, Republic of Korea) Corresponding author
• 신다혜(국방과학연구소 국방소재, 에너지 센터) | Dahye Shin (Defense Materials & Energy Technology Center Team 1, Agency for Defense Development, Daejeon, 34186, Republic of Korea) Corresponding author