Gate-tunable diode and photovoltaic effect in an organic–2D layered material p–n junction

Abstract

The semiconducting p-n junction is a simple device structure with great relevance for electronic and optoelectronic applications. The successful integration of low-dimensional materials in electronic circuits has opened the way forward for producing gate-tunable p-n junctions. In that context, we present here an organic (Cu-phthalocyanine)-2D layered material (MoS2) hybrid p-n junction with both gate-tunable diode characteristics and photovoltaic effect. Our proof-of-principle devices show multifunctional properties with diode rectifying factors of up to 10(4), while under light exposure they exhibit photoresponse with a measured external quantum efficiency of ∼11%. As for their photovoltaic properties, we found open circuit voltages of up to 0.6 V and optical-to-electrical power conversion efficiency of 0.7%. The extended catalogue of known organic semiconductors and two-dimensional materials offer the prospect for tailoring the properties and the performance of the resulting devices, making organic-2D p-n junctions promising candidates for future technological applications.

Optoelectronic Devices Based on Atomically Thin Transition Metal Dichalcogenides

“…Vertical p-n junction devices using other material combinations, such as GaTe/MoS 2 [104] and organohalide perovskite/WSe 2 [105], the formation of a p-n junction by surface charge induced doping [106], as well as organic/inorganic material junctions [107][108][109] have been demonstrated and gave similar results.…”

Trap-mediated electronic transport properties of gate-tunable pentacene/MoS2 p-n heterojunction diodes

“…The ideality factor of our device was between 2.2 and 22.2, which is much higher than the typical value of the ideality factor (between 1 and 2) observed for conventional p-n semiconductor junctions42. A large ideality factor value is a common feature of vdW heterostructure devices that results from the trap state171819. Because the ideality factor varies with the gate voltage, it suggests that the influence of the trap density on the charge transport conduction of the pentacene/MoS 2 p-n heterojunction device also depends on the gate voltage.…”

“…Here, one end of the MoS 2 channel was in contact with the Ti/Au, and one end of the pentacene channel was in contact with Au. Note that because the work function of Ti (~4.3 eV) and Au (~5.1 eV) are close to the electron affinity of MoS 2 (~4.2 eV)1832 and the highest occupied molecular orbital (HOMO, ~4.9 eV)33 of pentacene, these metal contacts can provide good electrical contacts on MoS 2 and pentacene. More detailed information about the fabrication process is provided in the Supplementary Information (Fig.…”

“…In particular, many efforts have been made to demonstrate the novel physical phenomena in vertically and laterally stacked 2D layered materials and their heterostructures131415. Most recently, there have been a few studies on vdW heterostructures based on 2D TMDCs combined with organic materials16171819202122232425. Organic materials have several favourable features, such as flexibility, low-cost production, low-temperature processing, and a lack of dangling bonds of organic materials2627.…”

“…Organic materials have several favourable features, such as flexibility, low-cost production, low-temperature processing, and a lack of dangling bonds of organic materials2627. Previous studies demonstrated the gate-tunable electronic and optoelectronic characteristics in vdW organic/inorganic p-n hybrid heterostructures161819202122232425. In particular, Jariwala et al .…”