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Hot-carriers, that is, charge carriers with an effective temperature higher than that of the lattice, may contribute to the high power conversion efficiency (PCE) shown by perovskite-based solar cells (PSCs), which are now competitive with silicon solar cells. Hot-carriers lose their excess energy in very short times, typically in a few picoseconds after excitation. For this reason, the carrier dynamics occurring on this time scale are extremely important in determining the participation of hot-carriers in the photovoltaic process. However, the stability of PSCs over time still remains an issue that calls for a solution. In this work, we demonstrate that the insertion of graphene flakes into the mesoscopic TiO2 scaffold leads to stable values of carrier temperature. In PSCs aged over 1 week, we indeed observe that in the graphene-free perovskite cells the carrier temperature decreases by about 500 K from 1800 to 1300 K, while the …
American Chemical Society
Publication date: 
22 Jan 2019

P O’keeffe, D Catone, A Paladini, F Toschi, S Turchini, L Avaldi, F Martelli, A Agresti, S Pescetelli, AE Del Rio Castillo, F Bonaccorso, A Di Carlo

Biblio References: 
Volume: 19 Issue: 2 Pages: 684-691
Nano letters