Enhanced PEDOT:PSS/n-Si Schottky photodetectors via nanostructure engineering: role of borophene and Si nanorods

This study presents a comparative investigation of nanostructure-engineered PEDOT:PSS/n-Si Schottky photodetectors incorporating borophene and silicon nanorods (Si NRs) to enhance interfacial charge transport and photodetection performance. Both nanostructures were embedded into the PEDOT:PSS matrix, modifying the hybrid film's structural, optical, and electronic properties. Characterization using HRTEM, SAED, XRD, FTIR, UV–Vis spectroscopy, and cross-sectional SEM, combined with electrical and optical measurements, shows that borophene and Si NRs enhance light absorption, reduce the effective optical band gap, and improve carrier transport across the Schottky junction. Compared to pristine PEDOT:PSS/n-Si devices, the nanostructure-engineered photodiodes exhibit improved rectifying behavior, higher forward current, and better diode quality, indicating reduced interfacial barriers and more efficient charge extraction. Under self-powered operation (0 V), the borophene–PEDOT:PSS/n-Si device exhibits the highest detectivity of 3.06 × 109 Jones at a solar light intensity of 20 mW/cm2. When operated under a −2 V reverse bias at the same illumination intensity, the borophene–PEDOT:PSS/n-Si photodiode achieves its maximum performance, with a responsivity of 6.232 A/W and a detectivity of 1.13 × 1012 Jones, accompanied by the lowest noise-equivalent power (NEP) of 6.49 × 10−13 W·Hz−1/2. The Si-nanorods–PEDOT:PSS/n-Si device demonstrates comparable performance, exhibiting a responsivity of 6.165 A/W, a detectivity of 1.12 × 1012 Jones, and an NEP of 7.20 × 10−13 W·Hz−1/2 under a solar light intensity of 20 mW/cm2, confirming its strong photodetection capability. Under self-powered operation at different monochromatic wavelengths (351–1600 nm) with an incident light intensity of 20 mW/cm2, the Si NRs–PEDOT:PSS/n-Si device demonstrates the highest photocurrent across the UV–Visible–NIR spectrum, with corresponding photosensitivity of 2.13, responsivity of 14.20 mA/W, detectivity of 2.22 × 109 Jones, and external quantum efficiency (EQE) of 1.76%. The Borophene–PEDOT:PSS/n-Si device shows moderate enhancement, while the pristine PEDOT:PSS/n-Si device exhibits the lowest performance. Both borophene- and Si-nanorods–PEDOT:PSS hybrids show substantial performance improvements compared to the pristine PEDOT:PSS device. These results demonstrate that nanostructure-engineered PEDOT:PSS/n-Si junctions offer highly sensitive, broadband, and efficient photodetection.