Femtosecond Transient Absorption Spectra and Dynamics of Carrier Relaxation of Tin Perovskites in the Absence and Presence of Additives

Sudhakar Narra, Efat Jokar, Orion Pearce, Chia Yi Lin, Amir Fathi, Wei-Guang Diau*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

5 Scopus citations

Abstract

The effects of additives SnF2 (10%) and EDAI2 (1%) on the dynamics of carrier relaxation of formamidinium tin triiodide (FASnI3) perovskite were studied using femtosecond transient absorption spectra (TAS) with excitation at 600 and 870 nm. The TAS were analyzed according to a parallel sequential kinetic model with a global fit through singular-value decomposition. For excitation at 600 nm, two relaxation paths were found: one involved hot and cold carriers in the bulk state undergoing shallow bulk-defect-mediated charge recombination; the other involved trap carriers in the surface state undergoing deep surface-defect-mediated charge recombination. For excitation at 870 nm, only cold carriers were subjected to the bulk-state relaxation channel. Our spectral results indicate significant effects of the additives on retarding charge recombination in both bulk and surface states as well as decreasing the bandgap renormalization energy, the bandwidth of the photobleaching (PB) band, and the Stokes shift between the PB and photoluminescence bands, explaining how the device performance of FASnI3 solar cells became enhanced in the presence of SnF2 and EDAI2.

Original languageEnglish
Pages (from-to)5699-5704
Number of pages6
JournalJournal of Physical Chemistry Letters
Volume11
Issue number14
DOIs
StatePublished - 16 Jul 2020

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