Boosting efficiency of planar heterojunction perovskite solar cells by a low temperature TiCl₄ treatment

Abstract

It is well known that electron transport layer (ETL) plays an indispensable role in the planar heterojunction perovskite solar cells (PSCs). TiO2 is widely used as an ETL material due to its excellent transport properties, however, the presence of defects in the TiO2 layer diminishes the power conversion efficiency (PCE) of the devices. Herein, we introduce a method of low-temperature TiCl4 treatment to deposit a TiOx layer on the surface of TiO2 film, which can effectively passivate trap states at the TiO2 surface. Moreover, the treating process is optimized to be 30[Formula: see text]min using a 40[Formula: see text]mM TiCl4 aqueous solution. Benefiting from this, we obtain the champion device with the highest PCE of 18.47%, which is mainly due to the reduction of surface defects and the deposition of the well-crystallized perovskite films. Besides, the modified PSCs exhibit an average PCE of 17.59%, which is much better than the control devices.

Understanding the effect of TiCl4 treatment at TiO2/Sb2S3 interface on the enhanced performance of Sb2S3 solar cells

“…Other perspectives have taken place with TiCl 4 treatment at low temperatures (130 °C) to achieve a TiO 2 coating layer with a nonstoichiometric titanium dioxide, TiO x . By implementing this approach, the surface traps were effectively passivated [23] and the surface roughness reduced [24]. These results are interesting for flexible substrates, limited by the high temperature required for crystalline TiO 2 .…”

“…TiO 2 compact layer treated with TiCl 4 has also played an important role in the photovoltaic performance of perovskite solar cells (PSC) [22][23][24]. The post-heating process of TiO 2 films treated with TiCl 4 converts species from the TiCl 4 solution into TiO 2 surface crystals.…”

Enhanced efficiency of bifacial perovskite solar cells using computational study

“…In addition to extracting and transporting photo generated electron carriers, the ETL inhibits charge recombination by acting as a hole-blocking layer 9 . Due to its advantageous bandgap alignment, excellent electron mobility, chemical stability, and compatibility with various deposition methods, titanium dioxide (TiO 2 ) is commonly employed as an electron transport layer (ETL) 10 whereas HTL serves as an electron-blocking layer, facilitating hole flow while impeding electron movement 11 . To achieve the maximum power conversion efficiency, both layers are essential and require immaculate layers with low bulk and interface defects.…”

A novel, eco‐friendly film preparation process for improving the stability of organometal halide perovskite in solar cells

“…[2][3][4][5][6] These materials exhibit excellent photovoltaic properties such as high charge mobility, wide absorption range, and large optical absorption coefficient. [7] Among the halide perovskites, iodide (MAPbI3) perovskites are usually employed for their high absorptive capacity in the visible spectrum and small band gaps. [8][9][10] Many methodologies have been adopted for preparing perovskite films, including dipping, [11,12] spin coating, [13,14] screen printing, [15] and chemical evaporation [16] with increasing PCEs.…”