Visualizing carrier dynamics of a semiconductor film photodetector optimized by interface passivation

Area of Science:

• Materials Science
• Optoelectronics
• Physical Chemistry

Background:

• Semiconductor polycrystalline films are crucial for photodetector applications.
• Understanding carrier dynamics at grain boundaries is key to improving device performance.
• Interface passivation is a promising strategy to mitigate charge carrier losses.

Purpose of the Study:

• To investigate the impact of DMMI-Cl passivation on carrier diffusion in MASnBr3 polycrystalline films using transient absorption (TA) microscopy.
• To elucidate the effects of passivation on carrier recombination mechanisms.
• To evaluate the performance enhancement of photodetectors fabricated with passivated films.

Main Methods:

• Transient Absorption (TA) microscopy was utilized to study carrier diffusion.
• Carrier diffusion length and coefficient were measured before and after DMMI-Cl passivation.
• Recombination dynamics (monomolecular, bimolecular, and Auger) were analyzed.

Main Results:

• DMMI-Cl passivation increased carrier diffusion length from 109 nm to 123 nm.
• The diffusion coefficient improved from 0.119 cm² s⁻¹ to 0.151 cm² s⁻¹.
• Passivation suppressed monomolecular and Auger recombination while promoting bimolecular recombination, leading to a six-fold increase in photodetector responsivity (4.09 AW⁻¹).

Conclusions:

• TA microscopy is effective for studying carrier dynamics in passivated semiconductor films.
• DMMI-Cl passivation significantly enhances carrier transport and reduces recombination in MASnBr3 films.
• This study contributes to the development of high-performance tin-based perovskite photodetectors.