Facilitated Interfacial Electronic Processes by the π–π Stacked Edge-on Tetrabenzoporphyrin/Graphene Layer Enables Broadband Ultrasensitive Photodetecting with Prompt Response

Abstract

Developing efficient organic photodetectors and revealing the crucial factor affecting photodetection performances are of importance in varied applications and fundamental researches. In this work, 5,15-bisdodecyl-tetrabenzoporphyrin (C12TBP)/graphene (Gr) phototransistors were fabricated through in situ retro-Diels–Alder reaction (as-formed), which demonstrates ultrahigh responsivity and specific detectivity, fast response, and broad-band detecting abilities covering UV to near-IR radiations. The interfacial and bulk layers of C12TBP films, defined as the adlayer on Gr sheet and the other part of the films, respectively, were characterized in detail. The π–π stacked edge-on C12TBP/Gr interfacial layer is suggested as the key factor enabling the ultrasensitive photodetection through facilitating the multistep interfacial electronic processes for photocurrent generation. Frontier molecular orbitals overlap effectively in the neighbor π–π stacked C12TBP, which promotes not only the diffusion of photogenerated electron–hole pairs but also dissociation of electron–hole pairs and charge-transfer (CT) state through weakening the electron–hole binding by dispersing charges within C12TBP columns. The separation of CT state is boosted by the large distance between the holes in Gr and the electrons in the edge-on orientation of C12TBP as well. In addition, we found that the structural evolution of the interfacial layer has a significant difference from that of the bulk layers because of the strong adsorption to the substrate. The results provide valuable support for understanding the complicated relationship between the structures and electronic properties of interfacial layers and pave the way for fabricating high-performance organic photodetecting devices.

Recent advances in enhancing the photodetector performance of 2D materials by combining them with organic thin films

“…graphene/C 12 TBP heterojunction photodetectors (191 A W À1 , 3.9 Â 10 12 Jones) 122 using the in situ retro-Diels-Alder reaction. Notably, the authors investigated the impact of the interface layer stacking on photodetection capabilities and the underlying mechanism.…”

“…The interface layer may have a different arrangement from the bulk material, leading to an unclear understanding of the interface layer's optoelectronic properties and photodetection performance. Shao et al prepared high-performance graphene/C 12 TBP heterojunction photodetectors (191 A W −1 , 3.9 × 10 12 Jones) 122 using the in situ retro-Diels–Alder reaction. Notably, the authors investigated the impact of the interface layer stacking on photodetection capabilities and the underlying mechanism.…”

“…50,227 For instance, Shao et al employed edge-on C 12 TBP, stacked in a π–π configuration with graphene, inducing orbital coupling and hybridization to improve electron transfer at the interface. 122 Liu et al achieved high-quality interfaces by epitaxially depositing several layers of the organic small molecule C 8 -BTBT onto graphene, resulting in devices exhibiting high internal quantum efficiency (41%) and responsivity (1.8 × 10 5 A W −1 ). 133 Similarly, heterojunctions such as the self-assembled BTBT with MoS 2 have been explored.…”

Recent Progress in 2D Inorganic/Organic Charge Transfer Heterojunction Photodetectors

“…merged PbS QDs and graphene to promote the responsivity up to 10 7 A W −1 based on photogating. [ 102 ] Therefore, a planar CT heterojunction is adopted into 2D inorganic/organic initial devices, including dye, [ 103–105 ] polymer, [ 106–110 ] small molecule, [ 54,58,59,111–116 ] photocatalysts, [ 117 ] chlorophyll, [ 118 ] organic–inorganic perovskite, [ 119 ] COF, [ 83 ] and MOF. [ 84,120 ]…”

“…employed edge‐on 5,15‐bisdodecyl‐tetrabenzoporphyrin (C12TBP) with graphene to form a π–π stacked interface (orbit coupling and hybridization) to improve interfacial electronic transfer process. [ 112 ] The device show 2230 A W −1 responsivity covering 850 nm. Sun et al.…”