Hot carrier extraction in CH 3 NH 3 PbI 3 unveiled by pump-push-probe spectroscopy
Open Access
- 1 November 2019
- journal article
- research article
- Published by American Association for the Advancement of Science (AAAS) in Science Advances
- Vol. 5 (11), eaax3620
- https://doi.org/10.1126/sciadv.aax3620
Abstract
Halide perovskites are promising materials for development in hot carrier (HC) solar cells, where the excess energy of above-bandgap photons is harvested before being wasted as heat to enhance device efficiency. Presently, HC separation and transfer processes at higher-energy states remain poorly understood. Here, we investigate the excited state dynamics in CH3NH3PbI3 using pump-push-probe spectroscopy. It has its intrinsic advantages for studying these dynamics over conventional transient spectroscopy, albeit complementary to one another. By exploiting the broad excited-state absorption characteristics, our findings reveal the transfer of HCs from these higher-energy states into bathophenanthroline (bphen), an energy selective organic acceptor far above perovskite’s band edges. Complete HC extraction is realized only after overcoming the interfacial barrier formed at the heterojunction, estimated to be between 1.01 and 1.08 eV above bphen’s lowest unoccupied molecular orbital level. The insights gained here are essential for the development of a new class of optoelectronics.Funding Information
- Office of Naval Research (ONRGNICOPN62909-17-1-2155)
- National Research Foundation-Prime Minister’s office, Republic of Singapore (NRF-CRP14-2014-03)
- National Research Foundation-Prime Minister’s office, Republic of Singapore (NRF2018-ITC001-001)
- National Research Foundation-Prime Minister’s office, Republic of Singapore (NRF-NRFI-2018-04)
- Ministry of Education - Singapore (RG173/16)
- Ministry of Education - Singapore (MOE2016-T2-1-034)
- Ministry of Education - Singapore (MOE2017-T2-2-002)
- Nanyang Technological University (M4080514)
- Japan Society for the Promotion of Science (JSPS-NTU Joint Research Project M4082176)
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