The light detection performance of Al/DPAVBi/n-Si heterojunction for wide-range spectrum

The 4,4′-Bis[4-(di-p-tolylamino)styryl]biphenyl (DPAVBi) is a sky-blue fluorescent emitter and widely used in organic light emitting diodes (OLED) for improving optoelectronic behaviors. In this study, we employed DPAVBi as interfacial layer between Si and Al metal by spin coating technique to investigate its detection performance under various light power densities and across a broad spectrum from ultra-violet (UV) to near infrared (NIR). The crystallinity and surface morphology of DPAVBi layer were characterized by x-ray diffractometer (XRD) and scanning electron microscope (SEM). UV-Vis spectrometer was utilized to determine absorption behavior and band gap of DPAVBi layer. The diode and photodetector characteristics of the Al/DPAVBi/n-Si heterojunction were obtained by current voltage (I-V) and current-transient (I-t) measurements. According to thermionic emission theory, the Al/DPAVBi/n-Si heterojunction exhibited an ideality factor (n) of 4.07 and a barrier height (Фb) of 0.65 eV. The diode parameters were also confirmed by Cheung and Norde methods. The responsivity, photosensitivity, and specific detectivity values were also determined depending on the illumination of light power density and in the case wavelength. The Al/DPAVBi/n-Si heterojunction exhibited 0.89 A/W responsivity under sunlight. The wavelength-dependent photodetector parameters revealed that the Al/DPAVBi/n-Si heterojunction is more sensitive to light illumination in the visible region at a wavelength of 600 nm. The obtained results highlight that Al/DPAVBi/n-Si heterojunction can be employed as promising potential for optoelectronic applications in the visible range.