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Research Article |

Performance Optimization of ZnO/TiO2/NPB Heterojunction for Visible-Blind UV Photodetectors via SCAPS-1D Simulation

Author(s): Hajir Kh. Ibrahim1*, Noor Alhuda S. Al-Jammas1, Qais Th. Algwari1

Published In : International Journal of Electrical and Electronics Research (IJEER)        Volume 14, Issue 3

Publisher : FOREX Publication

Published : 30 September 2026

e-ISSN : 2347-470X

Page(s) : 706-715

DOI: https://doi.org/10.37391/IJEER.140305

Abstract

This work presents a detailed numerical optimization of an ITO/ZnO/TiO₂/NPB heterostructure for visible-blind ultraviolet (UV) photodetection. The device incorporates a thin TiO₂ interfacial layer between the inorganic ZnO electron transport layer and the organic NPB hole transport/absorbing layer. We systematically investigate the influence of layer thickness and doping and their corresponding dependency on the essential device performance characteristics in SCAPS-1D simulation tool, which is validated with available experimental data. The best performance of the photodetector occurs with a 110 nm NPB layer thickness among the tested thicknesses and an acceptor concentration of 10¹⁶ cm³ among the tested doping concentrations, yielding a photocurrent density of 0.440 mA cm⁻², a responsivity of 0.070 A W-1, and a QE of 23.47%. Following the 150 nm thickness of ZnO layer and donor concentration of 1020 cm-3, the figures now show increased Jsc to 0.4414 mA cm⁻², QE to 29.5%, and responsivity to 0.088 A W-1. The total device then exhibits a peak responsivity value of 0.088 A W-1 at -5 V bias, peaking near 370 nm and decreasing sharply toward the 410-420 nm cutoff. A key finding is that low NPB doping is important for reducing recombination losses. The optimized structure also has a high UV-to-visible rejection ratio.

Keywords: Organic Photodetector, ZnO, NPB, SCAPS-1D, Responsivity, Detectivity.




Hajir Kh. Ibrahim, Dept. of Electronic Engineering, College of Electronics Engineering, Ninevah University, Ninewa, Mosul City, Iraq; Email: hajar.khaleel@uoninevah.edu.iq

Noor Alhuda S. Al-Jammas, Dept. of Electronic Engineering, College of Electronics Engineering, Ninevah University, Ninewa, Mosul City, Iraq; Email: noor.abbas@uoninevah.edu.iq

Qais Th. Algwari, Dept. of Electronic Engineering, College of Electronics Engineering, Ninevah University, Ninewa, Mosul City, Iraq; Email: qais.najim@uoninevah.edu.iq

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Hajir Kh. Ibrahim, Noor Alhuda S. Al-Jammas, and Qais Th. Algwari (2026), Performance Optimization of ZnO/TiO2/NPB Heterojunction for Visible-Blind UV Photodetectors via SCAPS-1D Simulation. IJEER 14(3), 692-705. DOI: 10.37391/IJEER.140305.