We present the utilization of inorganic, organic, and hybrid (perovskite) thin film photodetectors in (bio)chemical sensing where OLEDs are used as the excitation source in compact devices. The sensitivity and feasible operational mode, whether monitoring the effect of the analyte concentration on the photoluminescence intensity or decay time following an OLED pulse will be discussed. While monitoring the PL decay time is the preferred operational mode, charge trapping and other defects impede the photodetectors’ response time, limiting the analysis dynamic range. Analytes tested include oxygen, glucose, lactate, and ethanol. Examples of all organic sensors for these analytes will be presented. The use of thin film photodetectors in on-chip (integrated all-organic) spectrometers will also be shown.
The dramatically reduction of cost of photodetectors without comprising their performance will enable new applications in many fields. In this talk, I will brief our progress in the development of sensitive photodetectors/photon counters using low-cost solution processable organic and nano-electronic materials. Four types of device structures will be compared in terms of device gain, noise, sensitivity, response speed and linear dynamic range: 1) traditional diode structure, 2) a structure combine the photodiode and photoconductor through the interface trap triggered secondary charge injection, 3) an organic phototransistor that has combined photoconductive gain and photovoltaic gain, and 4) quantum dots modulated transistor channel conductance. Broad response spectrum from UV to NIR will be demonstrated, and active material limited performance will be discussed.
Solution-Processed Nanoparticle Super-Float-Gated Organic Field-Effect Transistor as Un-cooled Ultraviolet and Infrared Photon Counter
Yongbo Yuan, Qingfeng Dong, Bin Yang, Fawen Guo, Qi Zhang, Ming Han, and Jinsong Huang*, Scientific Reports, 3, 2707 (2013)
A nanocomposite ultraviolet photodetector enabled by interfacial trap-controlled charge injection
Fawen Guo, Bin Yang, Yongbo Yuan, Zhengguo Xiao, Qingfeng Dong, Yu Bi, and Jinsong Huang*, Nature Nanotechnology, 7, 798-802, (2012)
Large Gain, Low Noise Nanocomposite Ultraviolet Photodetectors with a Linear Dynamic Range of 120 dB
Yanjun Fang, Fawen Guo,Zhengguo Xiao, Jinsong Huang*, Advanced Optical Materials, 348-353 (2014)
High Gain and Low-Driving-Voltage Photodetectors Based on Organolead Triiodide Perovskites
Rui Dong, Yanjun Fang, Jungseok Chae, Jun Dai, Zhengguo Xiao, Qingfeng Dong,Yongbo Yuan, Andrea Centrone,Xiao Cheng Zeng , Jinsong Huang*. ,Advanced Materials, 2015
Ultraviolet photodetectors have attracted increasing attention due to its widespread use in civilian
and military fields in the past decades. Many kinds of inorganic and organic materials have been
used for UV photodetectors so far. ZnO is one of the most prominent semiconductors among them,
because it has a wide-band-gap of ~3.35 eV and a large exciton binding energy of 60 meV. As for
ZnO nanostructures, they play important roles in developing UV photodetectors. It is fair to state that
ZnO nanostructures are probably the most important nanostructures that present excellent
performance in photodetectors. In this review, we will describe state-of-the-arts UV photodetectors
based on ZnO nanostructures and our recent progress on highly sensitive ZnO hybrid UV
photodetector with specific detectivity up to 3.4 ×10<sup>15</sup> Jones.
Organic solar cells (OSCs) have been extensively studied and significant improvements have been demonstrated in
recent years. Along with the excitement in technology development, the accurate measurement of OSCs has become
critical for the healthy development of this promising technology. The limited absorption and spectral response of
organic based solar cells could lead to significant derivation in solar cell measurement. In this paper, we will discuss
several issues in the measurement of organic solar cells, including spectral mismatch factor, elimination of the
mismatch by proper selection of reference cell, external quantum efficiency testing, device area issue etc. Results on
both polymer based bulk hetero-junction solar cell and small molecule based solar cell will be presented.
Recently conjugated polymers and conjugated organic molecules have drawn a great deal of attention, since they are uniquely suited for thin film, large area, mechanically flexible devices. On the other hand, polymer/inorganic nanocomposite have also been pursued to deliver unique electronic properties in various device applications such as organic light-emitting diodes, organic thin film transistors, and solar cells. Here we demonstrate a nanocomposite based on polyaniline nanofibers decorated with gold nanoparticles and apply this composite into memory devices. The electronic property shows an electric bistable effect in a two terminal sandwiched structure. These two bistable states have different conductivities by three orders of magnitude. The mechanism is likely involving electric-field induced charge transfer between the polymer and nanoparticles. This nanocomposite material provides a unique functionality and possibility to open a new direction for future organic electronics.