The crystal structure of Sb2S3 electrodes were examined by X-ray diffraction using a Rigaku SmartLab instrument (Cu Kα radiation) at 2 deg min -1 with a step width of 0.01 deg in 2θ-ω scan mode. Atomic Layer Deposition of TiO2: TiO2 was deposited by atomic layer deposition (ALD) using a Picosun R200 tool. The reactor temperature for deposition was 120 °C and the titanium precursor was tetrakis(dimethylamino)titanium (TDMAT), with water used as the oxygen source. The thickness of the ALD TiO2 was ~ 100 nm, as measured by ellipsometry on a silicon witness wafer.