Two‐Dimensional Material‐Enhanced Flexible and Self‐Healable Photodetector for Large‐Area Photodetection

Abstract

Flexible photodetectors are fundamental elements to develop flexible/wearable systems, which can be widely used for in situ health and environmental monitoring, human-machine interacting, flexible displaying, etc. However, the degraded performance or even malfunction under severe mechanical deformation and/or damage remains a key challenge for current flexible photodetectors. In this article, a flexible photodetector is developed with strong self-healing capability and stable performance under large deformation. This photodetector is made of the 2D material self-healing film by mixing 2D materials homogenously with the self-healing polymer of imidazolium-based norbornene polymerized with ionic liquids and counterions. The 2D material self-healing films show enhanced light absorption, and thus, decent photoresponse as compared to the pure self-healing film. The achieved photoresponse remains stable and even increases under small tensile strain within 150%, while decreases slightly under large tensile strain up to 1000%. Moreover, the photodetector not only can be fully recovered from repeated mechanical cuttings, but also presents excellent long-term stability in ambient condition for 500 days without showing any obvious degraded performance. Furthermore, a large-area 2D material self-healing photodetection array is designed with adjustable pixel size, which successfully recognizes the patterns of "T", "J", and "U".

Self-Healing Polymers for Electronics and Energy Devices

“…249,250 To overcome the performance degradation or even malfunction under severe mechanical deformation, An et al developed a mendable photodetector based on a composite material consisting of 2D materials (i.e., graphene, black phosphorus, or molybdenum disulfide) as the photoresponder and poly(ionic liquid) as the repairable matrix (Figure 35a). 251,252 The photoresponse of the composite stems from the photon-induced reduction in the resistance of the 2D materials. The self-healing of the composite is attributed to the strong ionic interactions between cations and anions of poly(ionic liquid), along with the strong interdiffusion of polymer chains resulting from the low T g .…”

“…(c) Dynamic photoresponse and (d) relative photocurrent of the photodetector after different cutting/healing cycles. Reprinted with permission from ref . Copyright 2021 Wiley-VCH.…”

Thickness Dependent Ultrafast Charge Transfer in BP/MoS2 Heterostructure

“…Since the discovery of graphene as a singleatom layer, [1] 2D materials possessing layered structures with the thick ness of a few atoms have attracted tremendous attention due to their unique optical, electronic, mechanical properties, etc. [2][3][4][5][6][7][8] Moreover, considering the strong intralayer chemical bonding and weak interlayer van der Waals (vdW) interac tions, one can establish various heterostructures via stacking dissimilar 2D materials vertically without the constraint of minimal lattice mismatch. Such heterostructures can exhibit new intriguing properties not seen in the individual building blocks and thus provide enormous opportunities for heterostructure and its dependence on the thickness of BP component.…”

Two-dimensional materials: synthesis and applications in the electro-reduction of carbon dioxide

“…2D materials are defined as a type of nanomaterials with a layer-like morphology and small thickness (normally 1-100 nm) in which electrons move on the nanoscale in two dimensions [25] . 2D materials have been developed for various applications, such as energy conversion [26][27][28] , catalysis [29][30][31] , sensing [32][33][34] , photodetector [35][36][37] , and memristor [38][39][40] , owing to their unique 2D geometry, nanoscale thickness, and high surface-to-volume ratio. 2D structures, such as nanoplates, nanosheets, and nanoflakes, have been using for preparation of various materials, including metals, metal oxides, metallic sulfides, and carbon materials [41][42][43][44] .…”