Photovoltaic Performance Enhancement of All‐Inorganic CsPbBr₃ Perovskite Solar Cells Using In₂S₃ as Electron Transport Layer via Facile Reflux‐Condensation Process

Abstract

All‐inorganic perovskite solar cells (PSCs) have attracted tremendous attention over the past few years owing to their outstanding thermal and moiture stability. Electron transport layers (ETLs) in PSCs play a prominent role of electron extraction and transportation as well as hole blocking for a high power conversion efficiency (PCE). Indium sulfide (In2S3) films have been introduced as a promising ETL of PSCs recently due to their high carrier mobility, appropriate band gap, and controllable electrical characteristics. Herein, a facile wet chemistry method is proposed to prepare In2S3 films for the ETLs of all‐inorganic CsPbBr3 PSCs with an architecture of fluorine‐doped tin oxide/In2S3/CsPbBr3/carbon. The resultant compact In2S3 films show a certain visible light absorption with a bandgap of 2.51 eV. With the optimal 3000 rpm speed of In2S3 spin‐coating, the best‐performing In2S3 based device presents a higher champion PCE of 5.83% with open circuit voltage of 1.34 V, a short circuit current density of 6.74 mA cm−2 and a fill factor of 0.65. The better performance of devices based on In2S3 ETLs is attributed to their more suitable energy level matching with less open circuit voltage loss, better light harvesting, and electron extraction capability enhancement.

A Novel Solvent for Multistep Solution‐Processed Planar CsPbBr3 Perovskite Solar Cells Using In2S3 as Electron Transport Layer

“…All the In 2 S 3 films were spin coated at the optimal speed of 3000 rpm and subsequently annealed at 300 °C in Ar atmosphere for 1 h according to our previous work. [ 40 ] The surface morphologies of the In 2 S 3 films obtained by four different reflux condensation temperatures are basically the same, which seem like many particle aggregates (about 100–150 nm) composed of smaller grains (about 10 nm), as shown in Figure 2 . However, when the reflux condensation temperature is 80 °C, the particle size is obviously smaller than the other three samples; while the temperature is 100 and 120 °C, the particle size is almost the same, which is between those of 80 and 140 °C; the particle size becomes larger as the temperature continues increasing up to 140 °C.…”

“…In our previous work, we have demonstrated that the electron extraction and transfer capability of the In 2 S 3 film from CsPbBr 3 perovskite film was superior to that of the TiO 2 film, compared with the FTO/CsPbBr 3 structure without In 2 S 3 or TiO 2 ETL. [ 40 ]…”

“…Therefore, in our previous work, we have put forward a facile and controllable reflux condensation technique in combination with the spin‐coating process to prepare In 2 S 3 thin films for the ETL of PSCs. [ 40 ] The influence of the spin‐coating speed of In 2 S 3 colloid precursor, which was derived from the reflux condensation process at 100 °C, on the morphologies of In 2 S 3 thin films and thus the device photovoltaic performance, has been investigated. The CsPbBr 3 PSCs with the architecture of fluorine‐doped tin oxide (FTO)/In 2 S 3 /CsPbBr 3 /carbon using In 2 S 3 thin film as ETL were fabricated.…”

Photovoltaic Performance Improvement of All‐Inorganic CsPbBr3 Perovskite Solar Cells by Antisolvent Assisted Crystallization

“…The CsPbBr 3 perovskite exhibits the most excellent heat, moisture, and ultraviolet light resistance, showing great potential applications in semitransparent or top-cell of tandem solar cells with Cu(In, Ga)Se 2 or crystalline silicon solar cells. [9][10][11][12][13][14] In the past several years, many important works have been done to improve the photovoltaic performance of CsPbBr 3 PSCs. Kulbak et al first proposed CsPbBr 3 as light absorption material, and the fluorine-doped tin oxide (FTO)/c-TiO 2 /m-TiO 2 / CsPbBr 3 /hole transport layer (HTL)/Au structured solar cell produced the highest PCE of 5.95 %, with open circuit voltage (V oc ) of 1.28 V, short current density (J sc ) of 6.24 mA/cm 2 and fill factor (FF) of 74 %.…”

“…However, both CsPbI 3 and CsPbI 3‐x Br x perovskites easily transform into non‐perovskite phase in air atmosphere, which hinders their practical applications. The CsPbBr 3 perovskite exhibits the most excellent heat, moisture, and ultraviolet light resistance, showing great potential applications in semitransparent or top‐cell of tandem solar cells with Cu(In, Ga)Se 2 or crystalline silicon solar cells [9–14] …”