An All‐Organic Self‐Powered Photodetector with Ultraflexible Dual‐Polarity Output for Biosignal Detection

Abstract

An organic photodetector (OPD), with organic semiconductors as photosensitive layer, has proved to rival that of a low-noise silicon photodetector, almost in all metrics [10] and has promising applications in health monitoring and image sensing. [11][12][13] In the meantime, flexible organic semiconductors are advantageous substitutes for inorganic semiconductors in wearable electronics because conformal thin-film devices can be manufactured with them, therefore, can better adhere and fit human skin. [14,15] Although organic semiconductors can make up for the poor flexibility of inorganic semiconductors to some extent, the metal-based or metal oxide electrodes in OPD remain a block to the realization of ultraflexible devices. [13] Simultaneously, metal-based or metal-oxide-based electrodes require vacuum thermal evaporation or electron beam deposition techniques that will complex the preparation process and increase production costs. [15] Introducing intrinsic flexible organic electrodes may help solve the above mentioned problems. The polymer conductor poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate), PH1000 (PH1000) with superb transmittance and conductivity, which can be fabricated by a simple solution method, has proved to be the most promising electrode in skin-like wearable electronics. [1] Dual-polarity photocurrent response endows optoelectronic devices with multifunctional characteristics that have proved to be applied in switchable light imaging, optical communication, and spectral bands' distinction. [16][17][18][19] While traditional p-n junction photo diodes should obey the physical principles of the unidirectional current migration, hence dual-polarity photocurrent response in the previous researches was realized by taking advantage of the concomitance among photovoltaic, photo-electrochemical, and photo-thermoelectric effects, [16,17,20,21] which has a high demand in selecting materials and fabricating devices. While in organic semiconductor systems, donors and acceptors blended to form interpenetrating bulk-heterojunction (BHJ) networks, [22] by reasonably designing the work functions of electrodes, migrations of electrons/holes can be effectively regulated thus can easily switch the polarity of electronic signals. [23,24] Distinctive characteristics of BHJ in OPD inspired us a straightforward and low-cost way in developing dual-polarity photocurrent response optoelectronic devices.In this work, we introduced transparent organic electrodes PH1000/PH1000 to fabricate an all-organic photodetector (all-OPD) with a vertically aligned structure PH1000/ poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate), Al 4083Endowing photodetectors with mechanically flexibility and actual functionality are current research issues in developing optoelectronic devices. However, rigid metal-based or metal-oxide-based electrodes remain a block to the realization of ultraflexible electronics. Thus, an ultraflexible all-organic photodetector (all-OPD) is designed by innovatively introducing symmetrical organic ...

Self‐Powered and Flexible Photodetector with High Polarization Sensitivity Based on MAPbBr3–MAPbI3 Microwire Lateral Heterojunction

“…Photodetectors are important optoelectronic components with applications in the fields of optical communication, detection, and sensing. [1][2][3][4][5][6][7][8] In recent years, organic-inorganic hybrid perovskite materials have been used as active layers in photodetectors owing to their strong light absorption, high carrier mobility, good mechanical flexibility, and solution preparation. [9][10][11][12][13][14] Owing to the tunable bandgap of perovskites, many nanoimprinting to improve crystal quality and successfully realized a high-performance CsPbI 3 -CsPbBr 3 lateral heterojunction photodetector.…”

Functionalized MXene Nanosheets and Al-Doped ZnO Nanoparticles for Flexible Transparent Electrodes

“…Highly transparent, conductive, and chemically stable electrodes are crucial factors for achieving high efficiency in photovoltaic and transistor devices. − The high transparency of the electrodes allows more photons to be harvested, thus leading to increased absorption. The excellent electrical conductivity, high optical transmittance, large chemical stability, low cost, and suitable band alignment of titanium-based MXenes make them ideal candidates for transparent electrodes. − The outstanding mechanical strength of MXenes also provides an opportunity to apply them as flexible electrodes in wearable electronic devices. − …”

Graphene-Coated Substrate-Mediated Photoresponse from MoS2/UCNP Nanohybrid-Based Photodetectors

“…10−12 Although limited by its absorption, the mechanical flexibility of graphene plays a crucial role in the fabrication of flexible PDs. 13,14 On the other hand, MoS 2 offers better optical absorption (in the visible region) with a tunable band gap from 1.2 to 1.9 eV for bulk and monolayer MoS 2 , respectively, 6 but has lower electronic mobility than that of graphene. Both MoS 2 6,15 and graphene 16 have been used in PDs with roles as the photoabsorber and charge transporter.…”