Abstract
Passivating surface and bulk defects of perovskite films has been proven to be an effective way to minimize nonradiative recombination losses in perovskite solar cells (PVSCs). The lattice interference and perturbation of atomic periodicity at the perovskite surfaces often significantly affect the material properties and device efficiencies. By tailoring the terminal groups on the perovskite surface and modifying the surface chemical environment, the defects can be reduced to enhance the photovoltaic performance and stability of derived PVSCs. Here, we report a rationally designed bifunctional molecule, piperazinium iodide (PI), containing both R2NH and R2NH2+ groups on the same six-membered ring, behaving both as an electron donor and an electron acceptor to react with different surface-terminating ends on perovskite films. The resulting perovskite films after defect passivation show released surface residual stress, suppressed nonradiative recombination loss, and more n-type characteristics for sufficient energy transfer. Consequently, charge recombination is significantly suppressed to result in a high open-circuit voltage (VOC) of 1.17 V and a reduced VOC loss of 0.33 V. A very high power conversion efficiency (PCE) of 23.37% (with 22.75% certified) could be achieved, which is the highest value reported for inverted PVSCs. Our work reveals a very effective way of using rationally designed bifunctional molecules to simultaneously enhance the device performance and stability.
| Original language | English |
|---|---|
| Pages (from-to) | 20134-20142 |
| Number of pages | 9 |
| Journal | Journal of the American Chemical Society |
| Volume | 142 |
| Issue number | 47 |
| Early online date | 16 Nov 2020 |
| DOIs | |
| Publication status | Published - 25 Nov 2020 |
| Externally published | Yes |
Bibliographical note
Publisher Copyright:© 2020 American Chemical Society.
Funding
This work was supported by APRC Grants of the City University of Hong Kong (9380086 and 9610421), Innovation and Technology Bureau supported programs (ITS/497/18FP and GHP/021/18SZ), the Guangdong-Hong Kong-Macao joint laboratory of optoelectronic and magnetic 6bal materials (no. 2019B121205002), an ECS grant (CityU 21301319), a Collaborative Research Fund grant (C5037-18G) from the Research Grants Council of Hong Kong, the Natural Science Foundation of Guangdong Province (2019A1515010761), the Guangdong Major Project of Basic and Applied Basic Research (no. 2019B030302007), the Air Force Office of Scientific Research (FA9550-18-1-0046), and a Teaching Start-Up Grant of the City University of Hong Kong (6000672). Z.Z. and A.J. are grateful for the technical support provided by Mr. Shekman Yiu for single-crystal analysis.
