Download Factors Affecting the Stability and Performance of Transient

Factors Affecting the Stability and Performance of
Transient Photodetectors
Simon Dalgleish, Louisa Reissig, Laigui Hu, Michio M. Matsushita, Kunio Awaga
Laboratory of Advanced Materials, Nagoya University, Japan
Compared to organic solar cells, organic photodetectors have received relatively little
attention, despite the obvious benefit of precise wavelength targeting of the organic
materials. Previous research has focused on tuning the wavelength of the
photoabsorber within conventional solar cell architectures, with few notable
exceptions. However, in order to optimize organic photodetection, attention must be
paid to the differences in purpose rather than the similarities.
Our strategy has been to employ a metal/semiconductor/insulator/metal (MISM)
structure to enhance the peak photocurrent at the expense of a steady-state
photocurrent. The resultant time-varying photoresponse (transient response), while
not being suitable for steady-state applications such as solar cells, is applicable to
telecommunications, where information is transferred in the form of a periodic light
signal of high frequency.
Efforts are ongoing to optimize each component of the MISM architecture, but one
recent successful strategy has been to incorporate ionic liquids as the insulator layer in
the device. Due to some unique properties of the ionic liquids, great improvements in
device efficiency and processing simplicity have been realized, and have led to the
development of an “on-tip” photodetector, where an optical fiber can serve as an
electrode, simply by dipping into the ionic liquid. The soft processing conditions for
such devices have prompted us to investigate biomimetic photodetectors using
photoactive proteins, such as rhodopsins, which are incompatible with conventional
solid-state device architectures.