Abstract : We measure the surface of CH33 NH33 PbI33 single crystals by making use of two photon photoemission spectroscopy. Our method monitors the electronic distribution of photoexcited electrons, explicitly discriminating the initial thermalization from slower dynamical processes. The reported results disclose the fast dissipation channels of hot carriers (0.25 ps), set a upper bound to the surface induced recombination velocity (< 4000 cm/s) and reveal the dramatic effect of shallow traps on the electrons dynamics. The picosecond localization of excited electrons in degraded CH33 NH33 PbI33 samples is consistent with the progressive reduction of photoconversion efficiency in operating devices. Minimizing the density of shallow traps and solving the aging problem may boost the macroscopic efficiency of solar cells to the theoretical limit.
Zhesheng Chen 1 Min-I Lee 2 Zailan Zhang 3 Hiba Diab 4 Damien Garrot 5 Ferdinand Lédée 4, 6 Pierre Fertey 7 Evangelos Papalazarou 2 Marino Marsi 2 Carlito Ponseca 8 Emmanuelle Deleporte 4, 6 Antonio Tejeda 2 Luca Perfetti 1
1 LSI – Laboratoire des Solides Irradiés
2 LPS – Laboratoire de Physique des Solides
3 IMPMC – Institut de minéralogie, de physique des matériaux et de cosmochimie
4 LAC – Laboratoire Aimé Cotton
5 GEMAC – Groupe d’Etude de la Matière Condensée
6 PPSM – Laboratoire de Photophysique et Photochimie Supramoléculaires et Macromoléculaires
7 SSOLEIL – Synchrotron SOLEIL
8 Lund University [Lund]
