# Zn(HQ)2-Phenanthroline/PEDOT:PSS Hybrid Film Engineering as a Promising Active Layer in Organic Photoconductive Devices

## TL;DR

A new hybrid film made of Zn(HQ)2-phen and PEDOT:PSS is developed for organic photoconductive devices, showing good performance on both glass and recycled substrates.

## Contribution

A novel Zn(HQ)2-phen/PEDOT:PSS hybrid film is engineered for use in flexible and efficient organic photoconductive devices.

## Key findings

- The hybrid film showed a maximum current of 1.8 × 10−2 A on TP–graphite and 1.1 × 10−2 A on glass–ITO under UV irradiation.
- The film exhibited a power output of 198 mW and 139 mW on TP–graphite for shortwave and longwave, respectively.
- The film's energy gap was measured as 3.5–3.8 eV, and it demonstrated mechanical properties suitable for flexible devices.

## Abstract

Zinc(II) bis(8-hydroxyquinolinate) (Zn(HQ)2) and 1,10-phenanthroline (phen) were combined to fabricate an organic semiconductor in a bulk heterojunction architecture and subsequently embedded in a poly 3,4-ethylene dioxythiophene–polystyrene sulfonate (PEDOT–PSS) matrix. The resulting Zn(HQ)2-phen/PEDOT–PSS was deposited as a film upon tin-oxide-coated glass and graphite-covered Tetra Pak (TP)-recycled substrates for the manufacture of organic photoconductive devices. The topographical and micromechanical characteristics of the hybrid films were assessed by atomic force microscopy, with an average roughness of 5.6 nm, maximum tensile strength of 7.95 MPa, and Knoop microhardness of 14.7. The fundamental energy gap (Eg) was determined employing the Kubelka–Munk function, with Eg of 3.5–3.8 eV. These results were complemented with a computational DFT molecular orbital analysis of the species involved in the hybrid semiconductor. The devices were electrically characterized under UV irradiation conditions, obtaining the current–voltage and power–voltage relationships. The maximum current in the TP–graphite device is 1.8 × 10−2 A and 1.1 × 10−2 A in the device on glass–ITO. Zn(HQ)2-phen/PEDOT–PSS film presents its own operating regimes relating to a photoconductor or flexible photoresistor. The power in the device on glass–ITO is 120 mW and 113 mW for shortwave and longwave, respectively, and in the device on TP–graphite, it is 198 mW and 139 mW.