Annealing-Free SnO₂ Layers for Improved Fill Factor of Perovskite Solar Cells

Abstract

Perovskite solar cells (PSCs) have developed rapidly with simplified planar structures, in which the electron transport layer (ETL) is one of the key components for high efficiency. As one of the most widely used ETLs for PSCs, a tin dioxide (SnO 2 ) ETL is usually obtained by thermal annealing at around 150 °C, which complicates the fabrication process and confines the application of PSCs onto thermally sensitive flexible substrates. Here, we adopted an annealing-free process for the first time, the negative pressure evaporation (NPE) method, to quickly prepare SnO 2 ETLs (NPE-SnO 2 ) within 1 minute at room temperature from widely used commercial aqueous SnO 2 colloid. The NPE process developed here significantly improves the surface morphology and conductivity of SnO 2 layers compared to the traditional thermally annealed ones (A-SnO 2 ). Detailed characterizations reveal that increased oxygen vacancies and reduced hydroxyl defects contribute to higher conductivity of NPE-SnO 2 and less interfacial recombination of PSCs. Therefore, a PSC with NPE-SnO 2 delivers an improved fill factor (FF) of 82.33% and a higher power conversion efficiency (PCE) of 23.07%, which is the highest value based on annealing-free SnO 2 . To conclude, the NPE process is a universal technique to obtain high-quality semiconductor films from their wet state within 1 min and opens up the possibility of fabricating functional layers of PSCs without thermal annealing.

Enhancing the Efficiency and Stability of Perovskite Solar Cells through Gradient Energy Band Tin Oxide Electron Transport Layer Design with Graphene Quantum Dot Incorporation

“…Hysteresis effect is an important parameter to measure the ETL capability (Figure e). The hysteresis index (HI) of two different samples is calculated by (PCE reverse –PCE forward )/PCE reverse . The HI of the single SnO 2 device is 0.103, and the HI of the device with GQDs is 0.065.…”

Robust electron transport layers of SnO2 for efficient perovskite solar cells: recent advances and perspectives

“…Wang et al first used the NPE process to rapidly prepare SnO 2 -ETL from commercial SnO 2 hydrocolloids at room temperature within 1 min. 95 The morphology and optical and electrical properties of SnO 2 were significantly improved compared to the traditional annealed ETL, and the champion PCE increased from 21.92% to 23.07%. The microwave-assisted reaction is a rapid technology to obtain SnO 2 quantum dots (QDs) with uniform morphology.…”

Recoverable Flexible Perovskite Solar Cells for Next‐Generation Portable Power Sources

“…The high strength of a flexible substrate can damage the flexibility of the resultant FPSCs, but low strength can cause difficulties in the preparation of the FPSCs. Usually, to achieve a balance between strength and flexibility, polymer substrates such as polyethylene terephthalate (PET) [16][17][18] and polyethylene naphthalate (PEN) [19][20][21][22] are chosen as flexible substrates. However, these polymer substrates have poor thermal stability.…”