Tuning of Molecular Aggregation and Photoresponse of Narrow-band Organic Photodetectors

Abstract

It is a great challenge to find suitable organic materials for developing narrow-band absorption organic photodetectors (NBA-OPDs) working in the deep-red and near-infrared spectral regions. In general, if dye molecules can form J-aggregates, their maximal absorption peak will red-shift and become narrower. In this work, a suitably structured pyrrolopyrrole cyanine (PPCy) with this unique property is realized for use in narrow-band photodetectors. It was found that the Coulomb and charge-transfer (CT) couplings of J-aggregates of PPCy can be tuned by the complexing boron group. Using poly[N,N′-bis(4-butylphenyl)-N,N′-diphenylbenzidine] (poly-TPD) as the donor and PPCy as the acceptor, the bulk heterojunction blends were prepared. The crystallinity and the crystal size of PPCy in the active layer can be changed by adjusting the weight ratio of the donor and the acceptor. Thus, the charge carriers' transportation in the device can be regulated. Furthermore, organic photodetectors with an adjustable narrow spectral response (full width at half-maximum, FWHM, 55−148 nm) in the 600−800 nm range have been prepared. In self-powered mode, the device's maximum specific detectivity (D*) is 2.1 × 10 13 jones, which is the largest value among the reported NBA-OPDs in this spectral range. Moreover, when the mass ratio of poly-TPD and PPCy-1 is 2:1, the device exhibits the narrowest FWHM of 55 nm, an ultrafast response speed with a rise time of 0.4 μs and a decay time of 0.8 μs, and the maximum linear dynamic range of 168 dB. This work paves the way to construct a high-performance NBA-OPD by tuning the molecular aggregation of PPCy.

Improved performance of ZnO based inverted organic photodetectors with morphological and interfacial modification

“…Assuming that the loose particle noise is the main noise under reverse bias, the D * is calculated by the following equation, 38,65 where q is the electric quantity carried by unit charge.…”

Improvement in Performance and Stability of PbS QD/IGZO Phototransistors Through the Introduction of Ga2O3 Film for Broadband Sensor Applications

“…The value of D * is measured as the output signal-to-noise ratio relative to the detection region. Given the sufficient low spectral noise density, shot noise was identified as the primary source affecting D * . PS is defined as the current variation due to light-induced EHPs.…”

Pyrrolopyrrole Cyanine J-Aggregate Nanoparticles with High Near-Infrared Fluorescence Brightness and Photothermal Performance for Efficient Phototheranostics

“…According to our previous research, PPCy tends to form an "edge-on" arrangement on silicon wafers. 40 Therefore, the difference in film thickness (H + l) of these three molecules was mainly attributed to the hindrance caused by their different coordination structures, resulting in different slip angles (γ) along the Y-axis direction during molecular stacking (Figure 3). This also aligned with the theoretical calculation results (Figure 2d−f).…”

“…To date, a few organic dye J-aggregates have been identified, such as cyanine dyes, porphyrin derivatives, BODIPY, and perylene bisimides. , Meanwhile, the repertoire of molecules capable of forming J-aggregates remains limited, and research elucidating the underlying mechanisms driving J-aggregate formation is also scarce. The PPCy dyes bear a structural resemblance to cyanine dyes and BODIPY, exhibiting similar physical properties like robust NIR absorption, high QY, and excellent photostability. − Recent studies have demonstrated the potential of PPCy dyes to form J-aggregates, which have been extensively utilized for applications of FLI, PTT, and photoacoustic imaging. − Nevertheless, the relationship between the molecular structure of PPCy and the resulting aggregate structure, as well as the physical properties of these aggregates, remains poorly understood. Furthermore, it is worth noting that these aggregates solely contribute to enhancing the FLI or PTT performance.…”