Investigation of photosensitive and photodetector characteristics of n-TPA-IFA/p-Si heterojunction structure

TL;DR

This study synthesized and characterized an n-TPA-IFA/p-Si heterojunction diode, demonstrating its potential as a photodetector with tunable photoresponse properties under different light intensities.

Contribution

It is the first to investigate the photosensitive and photodetector characteristics of n-TPA-IFA/p-Si heterojunctions, combining organic synthesis, theoretical calculations, and electrical measurements.

Findings

High rectification ratio (~10^4) indicating diode quality

Photoresponsivity and photosensitivity increase with light intensity

LDR improves with higher light intensities, suitable for image sensors

Abstract

n-TPA-IFA organic material was synthesized and deposited on p-Si by spin coating method to produce n-TPA-IFA/p-Si heterojunction diode. We determined that the dielectric constant and energy band gap of TPA-IFA organic material were 3.91 and 3.37 eV by DFT/B3LYP/6-311G(d,p) method using on Gaussian 09 W, respectively and the carrier type of TPA-IFA organic semiconductor material was also n-type at room temperature from temperature-dependent hall effect measurements. Using forward and reverse bias I-V measurements in the dark and under various light intensities, we examined the key electrical characteristics of the n-TPA-IFA/p-Si heterojunction diodeincluding, Qb and n. It was determined that the rectification ratio (RR) was approximately 104. The reverse current's observed increasing behavior with increasing light indicates that the produced heterojunction diode can be utilized as a photo-diode, detector, or sensor. The photodetector properties of n-TPA-IFA/p-Si heterostructure were explored at different light intensities, and the photoresponsivity (R), photosensitivity (PS), specific detectivity (D), and linear dynamic range (LDR) of the heterojunction found to be changed with reverse voltage and light intensity. It was found that as light intensity increased, the linear dynamic range (LDR), a crucial characteristic for image sensors, increased as well (10.15 dB and 18.84 dB for 20 and 100 mW/cm2). Ultimately, the findings confirmed that the TPA-IFA-based heterojunction diode could be obtained for the photodetector application.