题目: | Ultrafast Electron Transfer in Low-Band Gap Polymer/PbS Nanocrystalline Blend Films |
Wenping Guo1, Jianyu Yuan2, Haochen Yuan1, Feng Jin1, Lu Han2, Chuanxiang Sheng3, Wanli Ma2, and Haibin Zhao1 | |
1Shanghai Ultra-precision Optical ManufacturingEngineering Research Center and Key Laboratoryof Micro and Nano Photonic Structures(Ministry of Education)Department of Optical Science and Engineering,Fudan University 2Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices,Soochow University 3School of Electronic and Optical Engineering, Nanjing University of Science and Technology | |
摘要: | Ultrafast charge transfer dynamics in hybrid blend films of a low band-gap polymer poly(2,6-(N-(1-octylnonyl)dithieno[3,2-b:20,30-d] pyrrole)-alt-4,7-(2,1,3-benzothiadiazole)) (PDBT) and PbS quantum dots (QDs) are studied by using ultrafast transient transmission spectroscopy. It is observed that the transient bleaching signal arising from excitons of the PDBT displays a much faster recovery, within the time delay of≈5 ps, in hybrid films than in the neat PDBT film. In contrast, the bleaching signal resulting from the electron filling of the QDs in hybrid films shows an extra rising component during≈1–5 ps, which is absent in the pristine QDs. These results indicate the ultrafast electron transfer from the lowest unoccupied molecular orbital energy level of the PDBT to the conduction band of the QDs in the time scale of several ps after laser excitation. A transient absorption signal within 1 ps in the hybrid films is also found, indicating the emergence of charge transfer states (CTs). The CTs formed at the interface of the hybrid blend may facilitate the charge separation and transfer. It is estimated that over 80% of the photoexcited electrons in the PDBT may betransferred into the QDs. The transfer efficiencies show a positive correlation with the power conversion efficiencies of the corresponding hybrid solar cells. |
11.805 | |
1区 | |
http://onlinelibrary.wiley.com/doi/10.1002/adfm.201503556/abstract |
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