Enhanced interface properties of solution-processed antimony sulfide planar solar cells with n-type indium sulfide buffer layer

Although antimony sulfide (Sb2S3) has become a promising photovoltaic material, the performance of Sb2S3 planar solar cells is pinned by the charge recombination and interface defects of Sb2S3 thin film . Herein, n-type indium sulfide (In2S3) serving as the buffer layer between TiO2 and the Sb2S3 layers was prepared by chemical bath deposition (CBD) method. Sb2S3 thin films were in situ prepared with a solution-processed construction strategy. The characteristics of the obtained thin films were studied in more detail by electron microscopy, X-ray technique, optical and electrochemical performance measurements. Results show that the In2S3 buffer layer prepared by the optimized CBD time improves the compactness and crystallinity, prevents Sb3+ from being oxidized, and boosts the light absorption ability for the Sb2S3 films. The fabricated FTO/TiO2/In2S3/Sb2S3/P3HT/Au planar cell device exhibits the higher open-circuit voltage (Voc) of 0.59 V, short-circuit current density (Jsc) of 8.90 mA cm−2, and power conversion efficiency (PCE) of 2.41%, respectively, compared to the FTO/TiO2/Sb2S3/P3HT/Au cell device. The superior photoelectric conversion performance is attributed to the promoting effects of the In2S3 buffer layer at the interface between TiO2 and the Sb2S3 layers, which reduce the charge recombination, facilitate the electron transfer, and enhance the electron lifetime. This work proposes an original insight towards non-toxic In2S3 as a buffer layer in Sb2S3 planar solar cells.