Dedova, T.; Krautmann, R.; Rusu, M.; Katerski, A.; Krunks, M.; Unold, T.; Spalatu, N.; Mere, A.; Sydorenko, J.; Sibinski, M.; Oja Acik, I.: Sb2S3 solar cells with TiO2 electron transporting layers synthesized by ALD and USP methods. Solar Energy Materials and Solar Cells 280 (2025), p. 113279/1-10
10.1016/j.solmat.2024.113279
Open Accesn Version
Abstract:
Electronic characteristics were investigated for solar cells (SCs) based on FTO/TiO2/Sb2S3/P3HT/Au structure, employing TiO2 electron transport layers (ETLs) fabricated by two different methods: ultrasonic spray pyrolysis (USP) and atomic layer deposition (ALD). Regardless of the deposition method, both ALD and USP-TiO2 exhibit the anatase crystal structure. The calculated crystallite sizes, derived from the (101) reflection of TiO2 layers using the Scherrer equation, show minimal variance between the two methods, with values 25 nm for USP and 30 nm for ALD TiO2, respectively. Optical band gaps (Eg) were found to be 3.31 eV and 3.35 eV for USP and ALD methods, respectively. Exploring the thickness series of ALD-TiO2, ranging from 100 to 1000 cycles (approximately 5–75 nm), solar cell performance was evaluated, with the highest power conversion efficiency (PCE) of 3.3 % achieved using ALD-TiO2 of 400 cycles (approximately 30 nm thick). Notably, SCs featuring USP TiO2 ETL layers, with a thickness of approximately 35–40 nm, outperform their ALD-TiO2 counterparts, improving PCE by 15 %, recording 4.0 % versus 3.3 %, respectively. This superiority in PCE is attributed to the more favorable conduction band minimum (CBM) position of USP-TiO2 relative to the Fermi level, as revealed in the band diagram. Specifically, a lower CBM spike at the USP-TiO2/-Sb2S3 interface indicates reduced recombination rates compared to those at the ALD-TiO2/-Sb2S3 interface. This study offers valuable insights into enhancing SC performance by optimizing deposition methods and synthesis parameters of ETL layers.