Top illuminated organic photodetectors with dielectric/metal/dielectric transparent anode

Vacuum‐Processed Small Molecule Organic Photodetectors with Low Dark Current Density and Strong Response to Near‐Infrared Wavelength

“…This phenomenon could be attributed to the cumulative result of the optical cavity effect related to the optimized thickness of the active layer as well as the reduction in trap-assisted recombination due to the larger grain sizes in the thicker active layers. [22,39,47,48] As expected, the responsivity of OPD devices (see Figure 5b) also follows a similar trend as EQE data. The OPD device with the active layer thickness of 80 nm shows the highest EQE and responsivity of 74.6% and 0.439 A W -1 , respectively, at the wavelength of 730 nm under a bias of −2 V, while an active layer thickness of 60 nm outperforms slightly in the wavelength range of 350 to 450 nm (see Table S1 for details, Supporting Information).…”

“…The drastic decrease in leakage current (three orders of magnitude) for the OPD device with the active layer thickness of 80 nm insinuates the effective suppression of charge carriers injection from the electrodes by the blocking layers. The thinner active layer is prone to have a surface morphology with defects, thus generating the lower shunt resistance (R SH ) that contributes to the increase of leakage current as reported by Kim et al [39] To further explore the interfacial phenomenon, impedance spectroscopic study was carried out to investigate the charge transfer resistance in bulk heterojunction. [12,[40][41][42] In the dark condition, the Nyquist-plot shows comparatively lower charge transfer resistance (R CT ) for the device with the active layer thickness of 20 nm under an AC signal ( Figure S2a, Supporting Information).…”

Bilayer Interdiffused Heterojunction Organic Photodiodes Fabricated by Double Transfer Stamping

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However, O 2 plasma treatment results in an increase of stamp surface adhesive energy, preventing efficient layer transfer from the PDMS to the substrate.

To address these problems, we introduce double transfer stamping (DTS) to promote interdiffusion between donor and acceptor layers to form well-defined interdiffused bilayer heterojunction (BiHJ) OPDs sandwiched between donor and acceptor layers that are in direct contact with their respective metal electrodes. [21] Although other approaches have been demonstrated to suppress dark current injection such as addition of a hole blocking layer (e.g., ZnO) [21,22] at the anode, or an electron blocking layer (e.g., poly[N,N′-bis(4butylphenyl)-N,N′-bis(phenyl)-benzidine]) at the cathode, [2] the success of these methods are fabrication process dependent since the additional layers can introduce interface states that adversely affect device performance. Using this approach, we demonstrate an inverted interdiffused P3HT/PCBM bilayer photodiode whose dark current density is 7.7 ± 0.3 nA cm −2 with an external quantum efficiency of 60% ± 1% and a peak specific detectivity of (4.8 ± 0.2) × 10 12 cm Hz 1/2 W −1 .

In Figure 1, we show the energy level diagram for the OPD to illustrate how donor and acceptor bilayer interdiffusion can effectively suppress the dark current under reverse bias while maintaining a high quantum efficiency; the energy values shown are found elsewhere.

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Dichroic Sb2O3/Ag/Sb2O3 Electrodes for Colorful Semitransparent Organic Solar Cells

“…[ 25,26 ] as both types of buffer layers may comprise semiconducting metal oxides which may exhibit suitable dielectric properties for use in DMD electrodes. For example, ITO/Ag/ITO, [ 27 ] MoO 3 /Ag/MoO 3 , [ 28–30 ] ZnS/Ag/ZnS, [ 31 ] and AZO/Ag/AZO [ 32,33 ] have been demonstrated in OSCs. In the case that DMD multilayers are used as top electrodes, the transmittance and reflectance can be adjusted by varying the refractive index of the dielectric and thickness of each layer.…”