Touch-on transfer development: Bilateral interdiffusion suppression based on dry fullerene derivative for precise perovskite photodetection

초록

Solvent penetration at the electron transport layer/perovskite interfaces induces interfacial mixing and charge trap formation, a fundamental performance-limiting mechanism in perovskite photodetectors. This study systematically analyzes solvent penetration mechanisms to address the inherent limitations of conventional wet [6,6]-phenyl-C₇₁-butyric acid methyl ester (PC₇₁BM) processing and validates the hypothesis that pristine interface formation enhances charge transport properties. We develop a solvent-isolated dry PC₇₁BM transfer process to fabricate a p-i-n perovskite photodetector architecture and quantitatively determine the impact of interface quality on charge transport characteristics. Space-charge-limited current measurements quantify trap density, and electrochemical impedance spectroscopy determines charge transfer resistance to verify interface optimization mechanisms. The transfer process implements bilateral interdiffusion suppression, improving surface roughness to 4.44 nm and optimizing the energy level of the lowest unoccupied molecular orbital to 4.28 eV, thereby reducing charge transfer resistance to 19.3 Ω (39.5% decrease) and suppressing trap density to 8.85 × 10 ¹ ⁴ cm⁻³ (67.6% reduction). This dry-transfer ETL deposition strategy reduces dark current density by 58.3% (8.51 × 10⁻⁹ A cm⁻²) and enhances detectivity by 60.4% (3.93 × 10 ¹² Jones), and the enhanced interfacial stability retains 99.7% of the photoresponsivity over 180 min. Photoplethysmography applications confirm the clear detection of the second derivative of cardiovascular characteristic waves, validating proof-of-concept biomedical demonstration of cardiac signal detection. This study presents performance enhancement mechanisms that suppress interfacial solvent penetration in perovskite photodetectors, providing novel design guidelines for developing high-performance optoelectronic devices.

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