Interfacial Study To Suppress Charge Carrier Recombination for High Efficiency Perovskite Solar Cells

Area of Science:

• Materials Science
• Renewable Energy
• Photovoltaics

Background:

• Perovskite solar cells are a promising next-generation photovoltaic technology.
• Efficient charge transport and minimized recombination are crucial for high device performance.
• The interface between the electron transport layer (TiO2) and the perovskite absorber layer plays a critical role.

Purpose of the Study:

• To investigate the effects of annealing conditions on the TiO2-perovskite interface and perovskite grain boundaries.
• To understand how annealing influences charge transport and recombination in perovskite solar cells.
• To optimize perovskite film preparation for improved solar cell efficiency.

Main Methods:

• Fabrication of perovskite films using single-step and sequential deposition techniques with varying annealing times.
• Nanoscale Kelvin Probe Force Microscopy (KPFM) for surface potential mapping and charge transport analysis.
• X-ray Diffraction (XRD) for phase analysis and transient analysis for carrier lifetime and transport time.

Main Results:

• Annealing conditions critically affect charge transport, with optimized conditions suppressing electron-hole recombination.
• Perovskite grain boundaries exhibit higher positive potentials (300-400 mV) after annealing, hindering back-recombination.
• Optimized devices show increased carrier lifetime and reduced carrier transport time, attributed to favorable grain boundary potential and band alignment.

Conclusions:

• Annealing is a key factor in controlling the TiO2-perovskite interface and perovskite film quality.
• Achieving optimal grain boundary potential and band alignment between TiO2 and perovskite is essential for high-performance solar cells.
• This study provides insights into optimizing perovskite solar cell fabrication for enhanced efficiency and stability.