While the power conversion efficiency (PCE) of colloidal quantum dot (CQD) solar cells can reach > 10%, the major obstacle for charge extraction and energy loss in such devices is the presence of surface trap sites within CQDs. In this work, highly trap-passivated PbS CQDs were developed using a novel iodide based ligand, 1-propyl-2,3-dimethylimidazolium iodide (PDMII). We examined the effects of PDMII on the surface quality of PbS-CQDs and compared them with TBAI, which is the best-selling iodide based ligand. By using PDMII, improved surface passivation with reduced sub-bandgap trap-states compared to TBAI was achieved. The reduced trap density resulted in enhanced charge extraction with diminished energy loss (0.447 eV) in the devices. Solar cell devices using our PDMII based CQDs displayed high PCE and air stability. The certified PCE of our PDMII based devices reached 10.89% and was maintained at 90% after 210 days of air storage.
Bibliographical noteFunding Information:
The authors gratefully acknowledge support from the New and Renewable Energy Core Technology Program of the Korea Institute of Energy Technology Evaluation and Planning (KETEP), granted financial resources from the Ministry of Trade, Industry and Energy, Republic of Korea (20163030013960), the Technology Development Program to Solve Climate Changes (2016M1A2A2940912) and Basic Science Research Program (2017R1A2B2009178) through the National Research Foundation (NRF) funded by the Ministry of Science, ICT & Future Planning, the National Research Foundation (NRF) Grant funded by the Korean Government (MSIP, No. 2016R1A5A1012966), and the Global Scholarship Program for Foreign Graduate Students at Kookmin University in Korea. This work was also partially supported by the Korea Institute of Science and Technology (KIST) Institutional Program.
All Science Journal Classification (ASJC) codes
- Renewable Energy, Sustainability and the Environment
- Materials Science(all)
- Electrical and Electronic Engineering