Phase-dependent broad-range photodetection by iron oxide nanorods

This study focuses on the multi-phasic iron oxide nanorods (IONRs) and evaluates their performance as photodetectors operational in broad spectrum ranging from UV to visible light. The IONRs were synthesized using a wet chemical co-precipitation (COP) method under varying reaction conditions that resulted in multi-phases of iron oxide. While sample labeled as COP1 consisted of mixed phases of α-FeOOH/α-Fe₂O₃/γ-FeOOH, the one labeled as COP2 showed ε-Fe₂O₃/γ-Fe₂O₃. Optical studies confirmed distinct energy bandgaps for IONRs samples. Transmission Electron Microscopy (TEM) showed a reduction in nanorod length from 60 \(\pm\) 8 (COP1) to 14 \(\pm\) 3 nm (COP2) and diameter from 5 \(\pm\) 0.5 nm to 3 \(\pm\) 0.5 nm. As-synthesized powder was cast as thin film on the screen-printed electrodes to measure photocurrent under UV and visible light illumination. Both the samples exhibited quick photoresponse under UV light illumination at a low bias voltage of 0.5 V, whereas the COP2 sample responded to visible light also. The synthesis of multi-phasic IONRs via a modified wet chemical method adds a versatile approach for altering their properties for enhanced photodetection applications and broadening the detection range.