Combination of Metal Oxide and Polytriarylamine: A Design Principle to Improve the Stability of Perovskite Solar Cells

Marina M Tepliakova,Eugene S Statnik,Pavel A Somov,Alexandra N Mikheeva,Keith J Stevenson,Alexander M Korsunsky

doi:10.3390/en14165115

Marina M Tepliakova, Eugene S Statnik + Show 4 more

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https://doi.org/10.3390/en14165115

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Abstract

In the last decade, perovskite photovoltaics gained popularity as a potential rival for crystalline silicon solar cells, which provide comparable efficiency for lower fabrication costs. However, insufficient stability is still a bottleneck for technology commercialization. One of the key aspects for improving the stability of perovskite solar cells (PSCs) is encapsulating the photoactive material with the hole-transport layer (HTL) with low gas permeability. Recently, it was shown that the double HTL comprising organic and inorganic parts can perform the protective function. Herein, a systematic investigation and comparison of four double HTLs incorporating polytriarylamine and thermally evaporated transition metal oxides in the highest oxidation state are presented. In particular, it was shown that MoOx, WOx, and VOx-based double HTLs provided stable performance of PSCs for 1250 h, while devices with NbOx lost 30% of their initial efficiency after 1000 h. Additionally, the encapsulating properties of all four double HTLs were studied in trilayer stacks with HTL covering perovskite, and insignificant changes in the absorber composition were registered after 1000 h under illumination. Finally, it was demonstrated using ToF-SIMS that the double HTL prevented the migration of perovskite volatile components within the structure. Our findings pave the way towards improved PSC design that ensures their long-term operational stability.

Highlights

The first application of a lead halide perovskite material in photovoltaic devices was reported in 2009, when perovskite was used as a light harvester for dye-sensitized solar cells, showing 3.8% efficiency [1]
Comparison of four metal oxides deposited using as inorganic counterparts of double we present the comparison of four metal oxides deposited using physical vaporvapor deposition (PVD) as inorganic counHTL, which enabled efficient of encapsulation the perovskiteofmaterial, providing terparts of double
The CH3 NH3 PbI3 perovskite layer was deposited from the solution, and the organic component of the doublelayer polymer polytriarylamine (PTAA) synthesized using Suzuki polycondensation was spin-coated atop the perovskite layer [40]

Summary

Introduction

The first application of a lead halide perovskite material in photovoltaic devices was reported in 2009, when perovskite was used as a light harvester for dye-sensitized solar cells, showing 3.8% efficiency [1]. The liquid electrolyte employed in the first reported work was soon substituted with the solid holetransport layer (HTL) material Spiro-OMeTAD, giving the all-solid-state perovskite solar cells (PSCs) 9.7% efficiency and 500 h stability [3]. The classical approach of using a mesoporous TiO2 scaffold as an electron transport layer (ETL) was found to be redundant, as the perovskite material itself demonstrated impressive charge transport characteristics [4]. After achieving reasonable efficiencies of more than 15%, the work on improving the long-term stability of perovskite solar cells began. The degradation mechanism of perovskite solar cells remains the subject of intense investigation. Several aspects of the complex mechanisms have been revealed in the literature

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