Synthesis of Au/poly(1,2-diphenylethylenediamine)/n-Si Hybrid Structures for Self-Powered UV Detection

In this study, a high-performance hybrid photodiode (Au/PDPEN/n-Si/Al) was fabricated using a poly(1,2-diphenylethylenediamine) (PDPEN) organic interface layer on an n-type silicon (n-Si) substrate, with Al as the contact metal. The PDPEN structures exhibited significant absorption in the 300–1100 nm region with a direct band gap of 2.4 eV, consistent with established literature values. Electrical characterization of the device revealed that the PDPEN layer effectively passivates the silicon surface states, with an ideality factor of 1.93 and a barrier height of 0.711. Photodiode performance was investigated under visible light (100 mW/cm²) and 395 nm UV light (23.5 mW/cm²). Experimental results showed that the device exhibited a high On-Off ratio of 493 at -1.5 V under 395 nm UV light. The maximum external quantum efficiency (EQE) was calculated as 33.27%, the sensitivity (Responsivity) as 0.106 A/W, and the specific detectability (D*) as 6.02 x 10¹¹ Jones. Furthermore, the device's normalized photo-dark current ratio (NPDR) of 2.25 × 10⁸ W⁻¹ demonstrates its superiority in preventing leakage current at the PDPEN interface and in improving signal quality.