Low-Temperature and Solution-Processed Amorphous WO(x) as Electron-Selective Layer for Perovskite Solar Cells

Area of Science:

• Materials Science
• Photovoltaics
• Nanotechnology

Background:

• Electron-selective layers (ESLs) are critical for efficient charge extraction in perovskite solar cells (PSCs).
• Low-temperature fabrication of ESLs is essential for developing flexible and cost-effective PSCs.
• Amorphous tungsten oxide (WO(x)) is explored as a potential alternative to conventional TiO2 ESLs.

Purpose of the Study:

• To develop a low-temperature solution-processed amorphous WO(x) thin film for use as an ESL in PSCs.
• To evaluate the performance of WO(x) ESLs in comparison to traditional TiO2 ESLs.
• To understand the charge recombination mechanisms affecting device performance.

Main Methods:

• Solution processing of amorphous WO(x) thin films at low temperatures.
• Fabrication of PSCs utilizing WO(x) as the ESL.
• Characterization of film properties (transmittance, conductivity) and device performance (efficiency, Jsc, Voc, FF).
• Electrochemical analysis to investigate charge recombination.

Main Results:

• Amorphous WO(x) thin films with nanocaves were successfully prepared at low temperatures.
• WO(x) ESLs demonstrated comparable light transmittance and higher electrical conductivity than TiO2.
• PSCs with WO(x) ESLs showed comparable overall efficiency, increased short-circuit current density (Jsc), but reduced open-circuit voltage (Voc).
• Electrochemical studies revealed that inherent charge recombination limits the open-circuit voltage and fill factor.

Conclusions:

• Solution-processed amorphous WO(x) is a promising candidate for low-temperature fabricated ESLs in PSCs.
• The material offers advantages in conductivity, but charge recombination needs to be addressed for further performance improvement.
• This work paves the way for flexible PSCs utilizing novel ESL materials.