Multifunctional Bilayer Template for Near-Infrared-Sensitive Organic Solar Cells

Abstract

For organic solar cells (OSCs) based on nonplanar phthalocyanines, it has previously been reported that a thin film composed of triclinic crystals with face-on (or flat-lying)-oriented molecules, typically obtained with a CuI template layer, is desired for optical absorption in the near-infrared (NIR) spectral region. However, this work demonstrates that for a PbPc-C donor-acceptor pair, less face-on orientation with a broader orientation distribution obtained with a new template layer consisting of a ZnPc/CuI bilayer is more desirable in terms of solar cell efficiency than the face-on orientation. A NIR-sensitive PbPc-C OSC employing this bilayer-templated PbPc film is found to increase the internal quantum efficiency (IQE) by 36% on average in the NIR spectral region compared to a device using a CuI-templated PbPc film. Analyses of the change in IQE using the exciton diffusion model and the entropy- and disorder-driven charge-separation model suggest that the improved IQE is attributed to the facilitated dissociation of charge-transfer excitons as well as the reduction in exciton quenching near the indium tin oxide surface.

Photomultiplication type near‐infrared organic photodetectors with a mixed active layer

“…To further exploit the mechanisms, the absorption spectra of the films are investigated, as shown in Figure 4. It can be found that both the planar heterojunction and mixed active layers show two absorption bands at 730 and 900 nm in the NIR region, which can be assigned to the monoclinic and triclinic phase absorptions of PbPc, respectively 15‐19 . The PbPc (60 nm)/C 60 (40 nm) planar heterojunction layer displays the highest triclinic phase absorption, while a lower ones for the PbPc (20 nm)/PbPc:C 60 (80 nm) mixed active layers, which is attributed to the decreased component of PbPc in the mixed active films.…”

“…It can be found that both the planar heterojunction and mixed active layers show two absorption bands at 730 and 900 nm in the NIR region, which can be assigned to the monoclinic and triclinic phase absorptions of PbPc, respectively. [15][16][17][18][19] The PbPc (60 nm)/C 60 (40 nm) planar heterojunction layer displays the highest triclinic phase absorption, while a lower ones for the PbPc (20 nm)/PbPc:C 60 (80 nm) mixed active layers, which is attributed to the decreased component of PbPc in the mixed active films. This trend is reverse to the EQE spectra of the devices shown in Figure 2, where the device with a 1:1 mixed active layer appears the highest response at the triclinic phase absorption region.…”

“…Among these compounds, lead phthalocyanine (PbPc) has been used for NIR photovoltaic devices owing to its small bandgap with an absorption band extended to about 1000 nm as well as a high extinct coefficient. [15][16][17] In this study, photomultiplication type NIR-OPDs are demonstrated both in PbPc/C 60 heterojunction and PbPc: C 60 mixed active layer devices. Compared with the planar heterojunction device, the mixed active layer devices exhibits a higher NIR response.…”

“…Metallophthalocyanines are often utilized in organic electronic devices due to their advantages in chemical and physical properties. Among these compounds, lead phthalocyanine (PbPc) has been used for NIR photovoltaic devices owing to its small bandgap with an absorption band extended to about 1000 nm as well as a high extinct coefficient 15‐17 . In this study, photomultiplication type NIR‐OPDs are demonstrated both in PbPc/C 60 heterojunction and PbPc:C 60 mixed active layer devices.…”

Hybrid Functional Analysis of Electronic Properties of Transition-Metal Phthalocyanines

“…KLYSKO, S.V. SYROTYUK, 2021 attractive for OPV due the possibility to convert light into electricity in the near-infrared (NIR) region [10][11][12].…”