Enhanced control of self-doping in halide perovskites for improved thermoelectric performance

Tianjun Liu; Xiaoming Zhao; Jianwei Li; Zilu Liu; Fabiola Liscio; Silvia Milita; Bob C Schroeder; Oliver Fenwick

doi:10.1038/s41467-019-13773-3

Enhanced control of self-doping in halide perovskites for improved thermoelectric performance

Nat Commun. 2019 Dec 17;10(1):5750. doi: 10.1038/s41467-019-13773-3.

Authors

Tianjun Liu^{1

2}, Xiaoming Zhao², Jianwei Li³, Zilu Liu³, Fabiola Liscio⁴, Silvia Milita⁴, Bob C Schroeder³, Oliver Fenwick^{5

6}

Affiliations

¹ School of Engineering and Material Sciences, Queen Mary University of London, Mile End Road, London, E1 4NS, UK.
² The Organic Thermoelectrics Laboratory, Materials Research Institute, Queen Mary University of London, Mile End Road, London, E1 4NS, UK.
³ Department of Chemistry, University College London, 20 Gordon Street, London, WC1H 0AJ, UK.
⁴ Istituto per la Microelettronica e Microsistemi (IMM)-Consiglio Nazionale delle Ricerche (CNR), Via Gobetti 101, 40129, Bologna, Italy.
⁵ School of Engineering and Material Sciences, Queen Mary University of London, Mile End Road, London, E1 4NS, UK. o.fenwick@qmul.ac.uk.
⁶ The Organic Thermoelectrics Laboratory, Materials Research Institute, Queen Mary University of London, Mile End Road, London, E1 4NS, UK. o.fenwick@qmul.ac.uk.

Abstract

Metal halide perovskites have emerged as promising photovoltaic materials, but, despite ultralow thermal conductivity, progress on developing them for thermoelectrics has been limited. Here, we report the thermoelectric properties of all-inorganic tin based perovskites with enhanced air stability. Fine tuning the thermoelectric properties of the films is achieved by self-doping through the oxidation of tin (ΙΙ) to tin (ΙV) in a thin surface-layer that transfers charge to the bulk. This separates the doping defects from the transport region, enabling enhanced electrical conductivity. We show that this arises due to a chlorine-rich surface layer that acts simultaneously as the source of free charges and a sacrificial layer protecting the bulk from oxidation. Moreover, we achieve a figure-of-merit (ZT) of 0.14 ± 0.01 when chlorine-doping and degree of the oxidation are optimised in tandem.

Publication types

Research Support, Non-U.S. Gov't