Inkjet-Printed Imbedded Graphene Nanoplatelet/Zinc Oxide Bulk Heterojunctions Nanocomposite Films for Ultraviolet Photodetection

Abstract

A ZnO sol–gel precursor (ZnOPr) and graphene nanoplatelets (GnPs) are mixed into a composite ink for inkjet printing photodetectors with bulk heterojunctions of ZnO/GnP on a heated SiO2/Si substrate. Heating of the SiO2/Si wafers at ∼50 °C was found optimal to prevent segregated droplets on the hydrophobic surface of the SiO2/Si substrate during printing. After printing the ZnO/GnP channels, thermal annealing at 350 °C for 2 h was performed for crystallization of ZnO and formation of the ZnO/GnP heterojunctions. The GnP concentration was varied from 0, 5, 20, and 30 mM to evaluate optimal formation of the ZnO/GnP bulk heterojunction nanocomposites based on ultraviolet photoresponse performance. The best performance was observed at the 20 mM GnP concentration with the photoresponsivity reaching 2.2 A/W at an incident ultraviolet power of 2.2 μW and a 5 V bias. This photoresponsivity is an order of magnitude better than the previously reported counterparts, including 0.13 mA/W for dropcasted ZnO-graphite composites and much higher than 0.5 A/W for aerosol printed ZnO. The improved performance is attributed to the ZnO/GnP bulk heterojunctions with improved interfaces that enable efficient exciton dissociation and the charge transport. The developed inkjet printing of sol–gel composite inks approach can be scalable and low cost for practical applications.

Applications of Ceramic/Graphene Composites and Hybrids

“…In a different work, researchers used a ZnO sol-gel precursor that was mixed with GNP and deposited by inkjet printing on a heated Si/SiO 2 substrate (50 °C) to favor capillary bridging. The films were treated at 350 °C to nucleate ZnO and form multiple ZnO/GNP junctions; after testing for ultraviolet light (340 nm) detection, they proved better response than alike composites processed by other methods [ 344 ]. On the other hand, mix inks of ZnO nanopowders and graphene were prepared in two alcohols and polyvinylpyrrolidone media for inkjet printing films onto miniaturized complementary metal-oxide-semiconductor (CMOS) micro-hotplates to build portable sensors for breath diagnostics ( Figure 25 b).…”

Probing performance limiting factors in uncooled quantum dots/graphene SWIR-MWIR detectors

“…Interestingly, the UTA process can be applied to ZnO QD/Gr nanohybrids photodetectors for improved performance while graphene remains intact. 77,87 Since the graphene channel of higher carrier mobility provides a more efficient charge transport pathway than the ZnO QD film with lower carrier mobility, the overall better performance of the ZnO QD/Gr nanohybrids photodetectors than their QDs-only counterparts' is well justified. The QD/Gr interface can be another major limiting factor to the QD/Gr nanohybrids photodetectors performance since the nanohybrids devices rely on charge transfer across the interface.…”

Out‐of‐Plane Electronics on Flexible Substrates Using Inorganic Nanowires Grown on High‐Aspect‐Ratio Printed Gold Micropillars

“…[26,27] The 2D-printed PDs have been recently studied using inkjet, screen, and gravure printing. [28][29][30][31][32][33][34][35][36][37][38][39][40][41][42] Noticeably, most of the flexible 2D-printed PDs exhibit relatively lower responsivity and require a higher bias voltage. As the only flexible PD with 3D-printed or out-of-plane architectures, this work presents one of the best photoresponsive performance, exhibiting responsivity (3.16 × 10 5 A W −1 ), detectivity (2.62 × 10 17 Jones), and EQE (1.06 × 10 8 %) using low bias voltage (0.1 V) under low light intensity (1 μW cm −2 ).…”