Engineering of the Electron Transport Layer/Perovskite Interface in Solar Cells Designed on TiO₂ Rutile Nanorods

Abstract

The engineering of the electron transport layer (ETL)/light absorber interface is explored in perovskite solar cells. Single‐crystalline TiO2 nanorod (NR) arrays are used as ETL and methylammonium lead iodide (MAPI) as light absorber. A dual ETL surface modification is investigated, namely by a TiCl4 treatment combined with a subsequent PC61BM monolayer deposition, and the effects on the device photovoltaic performance were evaluated with respect to single modifications. Under optimized conditions, for the combined treatment synergistic effects are observed that lead to remarkable enhancements in cell efficiency, from 14.2% to 19.5%, and to suppression of hysteresis. The devices show JSC, VOC, and fill factor as high as 23.2 mA cm−2, 1.1 V, and 77%, respectively. These results are ascribed to a more efficient charge transfer across the ETL/perovskite interface, which originates from the passivation of defects and trap states at the ETL surface. To the best of our knowledge, this is the highest cell performance ever reported for TiO2 NR‐based solar cells fabricated with conventional MAPI light absorber. Perspective wise, this ETL surface functionalization approach combined with more recently developed and better performing light absorbers, such as mixed cation/anion hybrid perovskite materials, is expected to provide further performance enhancements.

Single-crystalline TiO2 Nanoparticles for Narrowing the Scalability Gap towards Stable and Efficient Perovskite Modules

“…One of the strategies to reduce charge transport losses is to change the morphology of TiO 2 nanocrystals. Random arrays of TiO 2 nanorods or nanowires-based electron transport layers (ETLs) have negligible performance enhancement on the FF 17 . However, ordered TiO 2 nanorods show promise due to their large surface area and combined with highly directional charge transport paths, resulting in low resistive losses.…”

Nanoscopically and uniformly distributed SnO2@TiO2/C composite with highly mesoporous structure and bichemical bonds for enhanced lithium ion storage performances

“…Titanium dioxide (TiO 2 ) has been regarded as a promising anode material in rechargeable lithium ion batteries (LIBs) due to its low cost, non-toxicity, and ultralow volume change (o4%) during lithium ion intercalation/deintercalation. 1,2 TiO 2 possesses a series of allotropes, such as anatase, 3,4 rutile, 5,6 and TiO 2 -B. 7,8 Among them, anatase TiO 2 has been widely investigated due to its inherent crystal structure for lithium ion storage.…”

Ordered array structures for efficient perovskite solar cells

“…Schmuki et al treated the surface of the TiO 2 nanorods with TiCl 4 and PC 61 BM. 65 The treated device exhibited a PCE of 19.5%, while the pristine device exhibited a PCE of 14.2%.…”

“…The well‐matched interface between SnO 2 and perovskite film and lower defects were believed to be the main reasons for improving PSCs stability. Schmuki et al treated the surface of the TiO 2 nanorods with TiCl 4 and PC 61 BM 65 . The treated device exhibited a PCE of 19.5%, while the pristine device exhibited a PCE of 14.2%.…”