Semitransparent Perovskite Solar Cells with Ultrathin Protective Buffer Layers

Area of Science:

• Materials Science
• Renewable Energy Engineering
• Solid State Physics

Background:

• Semitransparent perovskite solar cells (ST-PSCs) are crucial for tandem devices and see-through photovoltaics.
• Transparent conductive oxides (TCOs), often indium tin oxide (ITO), are standard transparent electrodes but are susceptible to damage during sputtering deposition.
• This sputtering damage negatively impacts the electrical performance of ST-PSCs.

Purpose of the Study:

• To develop an indium tin oxide (ITO) deposition process that minimizes sputtering damage in semitransparent perovskite solar cells (ST-PSCs).
• To investigate the efficacy of transition metal oxides (TMOs) as buffer layers for protecting ST-PSCs during ITO sputtering.
• To evaluate the performance and stability of ST-PSCs utilizing TMO buffer layers for applications in tandem solar cells and building-integrated photovoltaics.

Main Methods:

• Development of an ITO deposition process incorporating an ultrathin (<10 nm) transition metal oxide (TMO) buffer layer (vanadium oxide or molybdenum oxide).
• Fabrication and characterization of ST-PSCs with TMO buffer layers to assess electrical performance, parasitic absorption, work function, and oxygen vacancies.
• Performance testing of scaled-up 1 cm² ST-PSCs and evaluation of light-soaking stability (T80).

Main Results:

• Ultrathin vanadium oxide (V₂O₅) or molybdenum oxide (MoO₃) buffer layers effectively suppressed sputtering damage in ST-PSCs.
• Devices with TMO buffer layers exhibited minimal parasitic absorption, suitable work functions, and controlled oxygen vacancies.
• Achieved a highest fill factor (FF) of 76% and efficiency of 16.4% (less than 10% reduction compared to gold-based PSCs).
• Successfully scaled up to 1 cm² ST-PSCs with an FF of ~70% and efficiency of 15.7%.
• V₂O₅ offered superior near-infrared transmittance and significantly greater light-soaking stability (T80 of 600 h vs. 12 h for MoO₃).

Conclusions:

• Transition metal oxide (TMO) buffer layers, particularly ultrathin vanadium oxide (V₂O₅), are highly effective in preventing sputtering damage during ITO deposition for ST-PSCs.
• The developed method enables the fabrication of high-performance and stable ST-PSCs suitable for tandem applications and building-integrated photovoltaics.
• V₂O₅ emerges as a promising buffer layer material due to its excellent stability and optical properties, despite slightly lower initial efficiency compared to MoO₃.