Carrier Extraction from Perovskite to Polymeric Charge Transport Layers Probed by Ultrafast Transient Absorption Spectroscopy.

Esma Ugur, Jafar Iqbal Khan, Erkan Aydin, Mingcong Wang, Mindaugas Kirkus, Marios Neophytou, Iain McCulloch, Stefaan De Wolf, Frédéric Laquai

Research output: Contribution to journalArticlepeer-review

6 Scopus citations

Abstract

The efficiency of state-of-the-art perovskite solar cells is limited by carrier recombination at defects and interfaces. Thus, understanding these losses and how to reduce them is the way forward toward the Shockley-Queisser limit. Here, we demonstrate that ultrafast transient absorption spectroscopy can directly probe hole extraction and recombination dynamics at perovskite/hole transport layer (HTL) interfaces. To illustrate this, we employed PDPP-3T as HTL because its ground-state absorption is at lower energy than the perovskite's photobleach, enabling direct monitoring of interfacial hole extraction and recombination. Moreover, by fitting the carrier dynamics using a diffusion model, we determined the carrier mobility. Afterwards, by varying the perovskite thickness, we distinguished between carrier diffusion and carrier extraction at the interface. Lastly, we prepared device-like structures, TiO2/perovskite/PDPP-3T stacks, and observed reduced carrier recombination in the perovskite. From PDPP-3T carrier dynamics, we deduced that hole extraction is one order faster than recombination of holes at the interface.
Original languageEnglish (US)
Pages (from-to)6921-6928
Number of pages8
JournalThe Journal of Physical Chemistry Letters
Volume10
Issue number21
DOIs
StatePublished - Oct 22 2019

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