The dual role of ozone-treated aluminum doped zinc oxide for CH3NH3PbI3 solar cells

Chouhan, Arun Singh and Jasti, Naga Prathibha and Avasthi, Sushobhan (2019) The dual role of ozone-treated aluminum doped zinc oxide for CH3NH3PbI3 solar cells. In: ORGANIC ELECTRONICS, 66 . pp. 249-257.

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Abstract

We present perovskite solar cells using ozone-treated aluminum doped zinc oxide (AZO:O-3) in the dual role: as a transparent electrode and as an electron transport layer (ETL). Aluminum doped zinc oxide (AZO) replaces the conventional FTO/TiO2(c)/TiO2(m) stack, considerably simplifying the fabrication process and reducing thermal budget. Photoelectron spectroscopy suggests that AZO is an effective ETL for perovskite (CH3NH3PbI3) thin films, with a large valence band offset and a small conduction band offset, but with a possible path for carrier recombination at the interface. We show that treating the surface of AZO with ozone gas (AZO:O-3) improves the charge carrier extraction at the interface. Detailed characterization of the AZO:O-3/CH3NH3PbI3 interface shows that ozone reduces the oxygen vacancies and de-dopes top 6-9 nm of the AZO surface. The gradient in doping induces an electric-field at the AZO surface which enhances the carrier extraction. AZO:O-3/CH3NH3PbI3/spiro-OMeTAD/Au devices show champion J(SC), V-OC and eta of 20.92 mA/cm(2), 1.03 V and 10.5% respectively. Meanwhile, average short-circuit current density (J(SC)) has improved from 16.32 mA/cm(2) (AZO) to 19.74 mA/cm(2) (AZO:O-3). This is attributed to the induced electric-field at AZO:O-3 surface leading to an enhanced extraction of photo-generated charge carriers. Devices hysteresis is also much lower than previously reported results.

Item Type:	Journal Article
Publication:	ORGANIC ELECTRONICS
Publisher:	ELSEVIER SCIENCE BV
Additional Information:	Copyright of this article belongs to ELSEVIER SCIENCE BV
Keywords:	AZO; Ozone-gas treatment; Electronic band-diagram; Interface; Perovskite
Department/Centre:	Division of Interdisciplinary Sciences > Centre for Nano Science and Engineering
Date Deposited:	29 Jan 2019 09:49
Last Modified:	29 Jan 2019 09:49
URI:	http://eprints.iisc.ac.in/id/eprint/61577

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