2, Imperial College London, London, , United Kingdom
3, King Abdullah University of Science and Technology (KAUST), Thuwal, , Saudi Arabia
Following the unprecedented rise in photovoltaic power conversion efficiency in the past five years, metal halide perovskites (MHPs) have emerged as a new class of photoactive materials that promise to dramatically impact the solar industry. Their extraordinary electrical and optical properties are currently undergoing extensive studies while being explored for numerous other applications that span beyond energy generation.[1-2] In particular, the realization of MHP photodetectors can enable a wide range of optoelectronic devices, including image sensors, night vision systems, healthcare monitor systems, optical communications and electro-optical circuitry. Among the different types of photodetectors, phototransistors not only combine the functionalities of photodiode and read-out circuits but also offer the ability to deliver high-gain-bandwidth detection with unparalleled photosensitivity due to their intrinsic gain characteristics.
Here, we report on a universal approach for realizing hybrid organic-perovskite photojunction transistors (HOPTs) with unmatched operating characteristics. The combination of perovskites and organic semiconductors allows precise control of the photoresponsivity beyond the fundamental properties of compositional materials for different transistor operation regimes. To shed light on this unusual, but highly versatile device property, advanced materials characterization techniques, such as Raman, photocurrent, and photoluminescence mapping with spatial resolution down to 1 µm, are used to study how the charge transport of photo-generated carriers takes place within the active region of the HOPTs.
By integrating multiple HOPTs, electro-optical circuits that are able to sense and process electrical as well as optical signals, are demonstrated. To the best of our knowledge, this is the first perovskites-based electro-optical circuitry demonstrated to date and paves the way to exciting new developments. Furthermore, by taking advantage of the large library of organic semiconductors in combination with recently developed hybrid perovskite compounds, we are able to demonstrate HOPTs capable of sensing photons with wavelengths beyond the optical spectrum (>800 nm) and in the near-infrared (NIR) region without compromising the device’s superior photosensitivity. The resulting HOPTs exhibit high photoresponsivity (~104) with the ability for low-light detection down to a few nW. Finally, in addition to the highly tuneable opto-electrical properties, these prototypical HOPTs are fully solution-processable at low temperatures (<100 °C), and as such highly compatible with the emerging sector of inexpensive, large-area printed opto/electronics.
 S. D. Stranks, H. J. Snaith, Nat. Nanotechnol. 2015, 10, 391-402.
 Y.-H. Lin, P. Pattanasattayavong, T. D. Anthopoulos, Adv. Mater. 2017, DOI: 10.1002/adma.201702838.