One- and two-photon photocurrents from tunable organic microcavity photodiodes

Abstract

We have constructed multilayer thin-film organic microcavity photodiodes with the photoactive layer comprised of a spin-coated conjugated polymer and an evaporated C60 layer. The electrodes are designed as semitransparent mirrors which form a resonant cavity structure. The photocurrent spectra show distinct maxima at the optical resonances of the cavities, which are located up to 200 nm below the fundamental optical transition of the polymer. The design allows a simple tuning of the spectral response by varying the layer thickness. Microcavity photodiodes are also shown to be highly sensitive two-photon detectors, which exhibit a factor 500 improvement in the two-photon response compared to devices without photonic confinement.

Efficiency and spectral performance of narrowband organic and perovskite photodetectors: a cross-sectional review

“…Within the realm of internally filtered devices, the highest EQE of IntF-1 devices is at 13.6% [73]; IOEF|PCL generally perform below 30% [48,67,68,73,84,114,135] (with the exception of the work of Higashi et al which reaches 51% with an optimised architecture) [69]; CCN works typically give EQEs in the 1%-20% range [33,34,85,86,98] (the work of Arca et al reaching an EQE of 47%, is an important exception) [73]. The EQEs of most microcavity-based photodetectors are less or much less than 25% [42,65,[136][137][138][139] (the only exception being found in the work of Tang et al [42] who achieved EQEs up to 50% through detailed modelling and design). This is reflective of the fact that internally filtered and microcavity-based strategies are typically prone to greater photoconversion losses.…”

“…Microcavity-based (organic) photodetectors fare well in terms of spectral width, with most implementations delivering ultranarrowband behaviour (FWHM EQE ≈15-50 nm, see figure 6(a)) [42,65,[136][137][138][139]. It is important to note, however, that microcavity-based devices also provide significant photoresponse in the spectral range where the photoactive material absorbs appreciably.…”

“…Internal filtering has been equally successful, with widths in the 60-80 nm range via IOEF|PCL [48,84,114], and down to 22 nm through CCN [86]. Green-selective microcavity-based devices have been demonstrated as capable of ultranarrowband photodetection (FWHM EQE at 35-50 nm) [136][137][138], provided that they are combined with input filtering to suppress their off-resonance response.…”

Picosecond transient photoconductivity in organic molecular crystals

“…[10][11][12][13] For example, ultrapure naphthalene single crystals have a hole mobility that increases from about 1 cm 2 /Vs at room temperature to more than 100 cm 2 /Vs below 30 K. 9,10 Recent transport measurements on high-purity tetracene single crystals have also shown an increase in carrier mobility as the temperature is lowered below 300 K. 8 There is also much interest in organic materials for light-emitting devices, 14,15 lasers, 16,17 solar cells, 18,19 and photodetectors. [19][20][21][22] In fact, a photodetector structure with sub-nanosecond response time and 75% quantum efficiency in the visible region has been demonstrated. 19,20 However, despite the many advances in organic electronics and photonics, the nature of photocarrier generation and transport in organic semiconductors is not completely understood and remains controversial even today.…”

Effects of interface reflection on the resonant condition for a microcavity with multilayers between cavity mirrors

“…This property has been widely used to improve the performance of optoelectronic devices such as light emitting diodes (LEDs) and photodetectors, by integrating the MC structure into the device [1][2][3][4]. Recently, intense investigation has been performed to incorporate a wavelength-scale MC structure into organic optoelectronic devices to improve the linewidth and quantum efficiency of both organic LEDs and organic photodetectors (OPDs) [5][6][7][8][9][10].…”