Perovskite Solar Cell‐Gated Organic Electrochemical Transistors for Flexible Photodetectors with Ultrahigh Sensitivity and Fast Response

Abstract

Photodetectors (PDs) are the building block of various imaging and sensing applications. However, commercially available PDs based on crystalline inorganic semiconductors cannot meet the requirements of emerging wearable/implantable applications due to their rigidity and fragility, which creates the need for flexible devices. Here, a high‐performance flexible PD is presented by gating an organic electrochemical transistor (OECT) with a perovskite solar cell. Due to the ultrahigh transconductance of the OECT, the device demonstrates a high gain of ≈106, a fast response time of 67 µs and an ultrahigh detectivity of 6.7 × 1017 Jones to light signals under a low working voltage (≤0.6 V). Thanks to the ultrahigh sensitivity and fast response, the device can track photoplethysmogram signals and peripheral oxygen saturation under ambient light and even provide contactless remote sensing, offering a low‐power and convenient way for continuous vital signs monitoring. This work offers a novel strategy for realizing high‐performance flexible PDs that are promising for low‐power, user‐friendly and wearable optoelectronics.

Flexible and Stretchable Organic Electrochemical Transistors for Physiological Sensing Devices

“…Benefitting from these advantages, FSOECT-based biosensors have been further developed by material optimization, structure engineering, as well as exploring new applications. Furthermore, there are impressive advances in fabrication with low-cost printing methods (e.g., 3D printing, room-temperature inkjet printing), [303,302] integration with novel power sources, [304,305] biocompatibility and mechanical compliance, [306,307] and new sensing approaches for early diagnosis of diseases. [308] However, many challenges remain for broad applicability and commercialization of OECTs, and particularly FSOECTs, for bio-/physiological sensing.…”

“…Inspired by this approach, FSOECT biased by an integrated perovskite solar cell was developed by Yan and co‐workers. [ 304 ] This device was used as wearable sensors for tracking photoplethysmogram signals and peripheral oxygen saturation under ambient environment.…”

Metallointercalated-DNA Nanotubes as Functional Light Antenna for Organic Photoelectrochemical Transistor Biosensor with Minimum Background

“…Photoelectrochemistry (PEC) has been a burgeoning technology in the field of advanced biosensing. − The intense interest in this arena arises from the advantages of semiconducting materials interfacing biological systems, the versatile interfacial interactions, and the reduced background due to the total separation and different energy types of the input (photons) and output (electrons) signals. Recent exploration of light-semiconductor-OECT interactions − has opened the light-controllable OECT with many new implementations and unknown possibilities. Among them, one of particular interest is the fusion between PEC and the OECT to realize an organic photoelectrochemical transistor (OPECT) with a minimum background, in which the rational light-matter interplay is of vital importance.…”

Halide Substituted Ammonium Salt Optimized Buried Interface for Efficient and Stable Flexible Perovskite Solar Cells

“…With the rapid development of wearable and self-powered flexible electronics, the demand for flexible solar cells is spreading. [1][2][3][4][5][6] Compared with other photovoltaic materials, metal halide perovskite has low-temperature processability, high flexibility, and ameliorated interfacial electron transfer. However, compared with the top surface, i.e., interface between hole transporting layer (HTL) and perovskite in n-i-p device, and interface between perovskite and electron transporting layer (ETL) in p-i-n device, emerging evidence demonstrates that massive pinholes and defects are inevitably formed at the buried interface, which is much larger than that within the film.…”

“…With the rapid development of wearable and self‐powered flexible electronics, the demand for flexible solar cells is spreading. [ 1–6 ] Compared with other photovoltaic materials, metal halide perovskite has low‐temperature processability, high flexibility, and compatibility with curved surfaces, which make them more advantageous in realizing flexible solar cells. [ 7,8 ] However, their power conversion efficiencies (PCEs) significantly lag behind those of their rigid counterparts despite the continuous improvements and optimizations, such as perovskite compositions, deposition procedures, and selective charge transporting.…”