CdS as Electron Transport Layer for Low‐Hysteresis Perovskite Solar Cells

Abstract

In order to achieve highly efficient perovskite solar cells in n–i–p geometry with little hysteresis, CdS is investigated as low‐cost, easily processable electron transport layer (ETL). For comparison, also perovskite solar cells without ETL or with low‐temperature processed compact TiOx as well as combinations of TiOx and CdS in dual layer ETLs are investigated. It is found that CdS strongly suppresses hysteresis and that even inverted hysteresis can occur, caused by the much higher electron mobility of CdS in comparison to TiOx. Additionally, SIMS depth profiles reveal that iodide diffusion is suppressed when CdS instead of TiOx is in contact to the perovskite layer. For cells which are processed in ambient atmosphere, a highest efficiency with CdS as ETL >10% with minimal hysteresis is achieved.

TiO2 Colloid‐Spray Coated Electron‐Transporting Layers for Efficient Perovskite Solar Cells

“…The low temperature processes applied in this study were chemical bath deposition (CBD). [39,40] The thickness of the thin TiO 2 layer formed on the FTO substrate by CBD was controlled by adjusting the concentration of the TiOCl 2 aqueous solution; then the resulting film was heat-treated at 100 °C for 1 h. Figure 3A shows the change in efficiency of the PSCs fabricated using the S-TiO 2 on the ul-TiO 2 , which were deposited by CBD for 1 h at 70 °C under a different TiOCl 2 concentrations (40, 100 and 200 mM). As shown in Figure 3a, increases in efficiency was observed when the TiOCl 2 concentration increased from 40 to 100 mM; then, the efficiency decreased again when the TiOCl 2 concentration reached at 200 mM.…”

Energy‐Band‐Controlling Strategy to Construct Novel CdxIn1‐xS Solid Solution for Durable Visible Light Photocatalytic Hydrogen Sulfide Splitting

“…Generally, pristine CdS usually exhibits a low photo-stability due to severe photocorrosion. [22][23][24][25][26][27][28] Hence, the influence of the introduction of In into the CdS on the photostability was investigated. As shown in Figure 2c, no obvious decrease of the photocatalytic activity was observed under light illumination with three cycles (3 h each cycle), demonstrating that the CI75 sample possesses a remarkable anti-photocorrosion ability and photostability under short-term illumination.…”

“…solid solution semiconductors is particularly interesting because of the mild synthesis condition, tunable energy band structure, and superior performance for H 2 production even in the absence of noble-metal co-catalysts. [25][26][27][28] However, these studies mainly focused on the following two directions. One is to modulate the band gap energy for realizing the excellent sunlight response.…”

“…Among them, metal sulfides have been verified as desirable catalysts for photocatalytic H 2 S decomposition . Particularly, CdS‐based sulfides have been regarded as one of the most promising catalysts for visible‐light‐induced H 2 generation owing to their outstanding visible‐light response and proper conduction band (CB) position . However, the photocorrosion phenomenon for CdS is generally observed during photocatalytic process due to the oxidation of S 2− by the photogenerated holes (CdS‐based catalysts + 2h + → Cd 2+ + S) .…”

“…Among them, the ternary chalcogenide Cd x M 1‐x S (M = Mn, Zn, etc.) solid solution semiconductors is particularly interesting because of the mild synthesis condition, tunable energy band structure, and superior performance for H 2 production even in the absence of noble‐metal co‐catalysts . However, these studies mainly focused on the following two directions.…”