# Laurie Phillips$${}^{*1}$$, Thomas Baines$${}^{1}$$, Oliver Hutter$${}^{1}$$, Annette Pressman$${}^{1}$$, Leon Bowen$${}^{2}$$, Budhhika Mendis$${}^{2}$$, Ken Durose$${}^{1}$$ & Jon Major$${}^{1}$$

Abstract

Antimony Selenide (Sb$${}_{2}$$Se$${}_{3}$$) is an emerging chalcogenide photovoltaic absorber material, with great promise for thin-film solar applications. In this work, we show that closed-spaced sublimation can be used to produce Sb$${}_{2}$$Se$${}_{3}$$ layers with large grains, and high efficiencies. We examine the material

{affiliations}
• Stephenson Institute for Renewable Energy, University of Liverpool, Liverpool, UK University of Durham, Durham, UK

• ## Introduction

Photovoltaics installations continue to grow exponentially. However, if solar is to make a substantial contribution to the switch to sustainable energy sources, new absorber materials are needed that are abundant for terawatt-scale manufacture. Silicon-based technologies dominate the market, as the promise of thin-film photovoltaics is yet to be fully realised. Copper indium gallium di-selenide (CIGS) and cadmium telluride (CdTe) have the most widely accepted thin-film technologies, with efficiencies in excess of 20%. However, the scarecity of indium and tellurium, and the toxicity of cadmium are limiting factors, difficult to overcome for more widespread adoption. The recent emergence of lead-halide-based perovskite absorbers, while rapidly acheiving similarly high efficiencies, still have stability issues and contain highly toxic lead. The relatively lower toxicity of Antinomy selenide (Sb$${}_{2}$$Se$${}_{3}$$), coupled with it’s low-cost and higher abundance, means it is a material that shows considerable promise as an alternative. A single phase V-VI binary chalcogenide, Sb$${}_{2}$$Se$${}_{3}$$ has a near-ideal band-gap of 1.1-1.3 eV, high absorption coefficient and theoretical work has suggested that grain-boundaries are likely to be relatively benign.(citation not found: natcomms) Solar cells using this material have been demonstrated by many methods including spin-coating, electro-deposition, and evaporation.

In this work, we demonstrate solar cells utilising Sb$${}_{2}$$Se$${}_{3}$$ deposited using closed-spaced sublimation (CSS), a technique widely employed for the fabrication of high-efficiency CdTe devices. CSS is a technique whereby material is sublimed from a source onto a substrate separated by a gap of millimeters. It is capable of producing films with large grains and high deposition rates, and can be scaled up for industrial manufacturing fairly easy due to modest vacuum and temperature requirements.

We show that Sb$${}_{2}$$Se$${}_{3}$$ deposited by CSS has exceptionally large grains…. other things…. and other thing.

The cells were deposited with a FTO/TiO$${}_{2}$$/Sb$${}_{2}$$Se$${}_{3}$$/P3HT/Au configuration to achieve cells with efficiencies of  5.5%.

## Physical Characterisation

### Introduction

Material grown using closed-space sublimation is most obviously different from other techniques in that it results in large grains. From the FWHM of the peaks in figure \ref{fig:XRD}

### Energy-dispersive X-ray

Figure 1 - XRD