Plasmon resonance modulated photoluminescence and Raman spectroscopy of diindenoperylene organic semiconductor thin film

Zhang, D.; Horneber, Anke; Mihaljević, Josip; Heinemeyer, U.; Braun, Kai; Schreiber, Frank; Scholz, Reinhard; Meixner, Alfred J.

doi:10.1016/j.jlumin.2010.09.008

Cited by 11 publications

(20 citation statements)

References 20 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Increasing the applied voltage to 2 V leads to a blue shift by about 50 nm and a pronounced vibronic structure, especially for shorter wavelengths, appears, which becomes more pronounced upon increasing the voltage to 4 V. However, a weak contribution of the broad featureless emission at the same position as the spectrum for low applied voltage is still present. The main EL peak positions are similar to those found by photoluminescence measurements in the literature [8,39,40].…”

Section: Photocurrent and Electroluminescence Spectrasupporting

confidence: 86%

Crystalline versus Amorphous Donor-Acceptor Blends: Influence of Layer Morphology on the Charge-Transfer Density of States

et al. 2020

View full text Add to dashboard Cite

Organic small molecule solar cells are used as a test bed to investigate the influence of film morphology on the density of charge-transfer (CT) states. CT states are considered as precursors for charge generation and their energy as the upper limit for the open-circuit voltage in organic donor-acceptor solar cells. In this study the influence of morphology for two perylene donors [crystalline diindenoperylene (DIP) versus amorphous tetraphenyldibenzoperiflanthene (DBP)] with almost identical ionization energy is investigated. As acceptor material, the fullerene C 60 is used. By combining device measurements with optical and low-energy ultraviolet photoelectron spectroscopy, a comprehensive picture is obtained that describes how morphology and the connected density of states (DOS) affect device performance and the spectroscopic signature of CT states. Especially for the crystalline donor material DIP, strong exponential tail states reaching far into the gap are observed, which can be related to the presence of grain boundaries. A voltage-dependent filling of these states is identified as the origin of a blue shift of electroluminescence spectra with increasing applied voltage. Different approaches are compared to study the influence of static and dynamic disorder in the description of CT emission and absorption spectra of organic solar cells. Despite the fact that both donors yield almost identical CT energy (and, thus, the same open-circuit voltage) the Stokes shift between photocurrent and electroluminescence spectra and, concomitantly, the width of the CT DOS varies by more than a factor of 2. We discuss this observation in terms of the donoracceptor reorganization energy as well as an additional line broadening by static disorder. Remarkably, the more crystalline donor DIP shows a significant deviation from a Marcus-type description, while this is not the case for the amorphous DBP. This highlights the importance of film morphology in organic solar cells.

show abstract

Section: Photocurrent and Electroluminescence Spectrasupporting

confidence: 86%

Crystalline versus Amorphous Donor-Acceptor Blends: Influence of Layer Morphology on the Charge-Transfer Density of States

et al. 2020

View full text Add to dashboard Cite

show abstract

“…The main EL peak positions are similar to those found by photoluminescence measurements, characterized by the 0-0 transition at E ≈ 2.14 eV, which is followed by pronounced vibronic progression with peak energies of 1.98 and 1.80 eV. 47,51 The broad band around 1.7-1.6 eV is assigned to an aggregate emission due to the high crystallinity of DIP. Apart from the spectra of the single-layer devices, Fig.…”

Section: Direct Spectroscopic Evidence For the Charge-transfer State supporting

confidence: 77%

“…The tiny peak at 1.1 eV is a multiphonon absorption due to vibrational stretching modes of C-H bonds, whereas the high-energy part (>2.25 eV) is due to π -π * transitions (for details see Ref. 47). In C 60 the increase of absorption already starts around 1.75 eV, in accordance with an optical gap commonly taken to be 1.9 eV.…”

Section: Direct Spectroscopic Evidence For the Charge-transfer State mentioning

confidence: 99%

Quantification of energy losses in organic solar cells from temperature-dependent device characteristics

et al. 2013

View full text Add to dashboard Cite

Owing to the excitonic nature of photoexcitations in organic semiconductors, the working mechanism of organic solar cells relies on the donor-acceptor (D/A) concept enabling photoinduced charge transfer at the interface between two organic materials with suitable energy-level alignment. However, the introduction of such a heterojunction is accompanied by additional energy losses compared to an inorganic homojunction cell due to the presence of a charge-transfer (CT) state at the D/A interface. By careful examination of planar heterojunctions of the molecular semiconductors diindenoperylene (DIP) and C 60 we demonstrate that three different analysis techniques of the temperature dependence of solar-cell characteristics yield reliable values for the effective photovoltaic energy gap at the D/A interface. The retrieved energies are shown to be consistent with direct spectroscopic measurements and the D/A energy-level offset determined by photoemission spectroscopy. Furthermore, we verify the widespread assumption that the activation energy of the dark saturation current E and the CT energy E CT may be regarded as identical. The temperature-dependent analysis of open-circuit voltage V OC and dark saturation current is then applied to a variety of molecular planar heterojunctions. The congruency of E and E CT is again found for all material systems with the exception of copper phthalocyanine/C 60 . The general rule of thumb for organic semiconductor heterojunctions, that V OC at room temperature is roughly half a volt below the CT energy, is traced back to comparable intermolecular electronic coupling in all investigated systems.

show abstract

“…The PL spectrum retains features that can be associated with vibronic structure, but whose relative intensities are completely different from those of the monomer. 43 The change in vibronic line shape can be taken as evidence for the formation of intermolecular exciton states. 33 The side-by-side herringbone packing motif, coupled with orientation of the transition dipole along the long axis of the molecule, would be expected to result in H-type aggregate states similar to what is observed in the oligothiophenes.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Excited-State Dynamics of Diindenoperylene in Liquid Solution and in Solid Films

et al. 2015

View full text Add to dashboard Cite

The excited-state dynamics of diindenoperylene (DIP) are investigated in dilute solution and in a solid film at room temperature using picosecond photoluminescence and femtosecond transient absorption measurements. In solution, DIP undergoes a rapid (0.89 ns) internal conversion back to its ground state, with no detectable formation of triplet or other long-lived states. In the solid state, multiple emissive species are formed. The time-resolved photoluminescence signal is dominated by an intrinsic exciton that decays on a time scale of 166 ps. Emission from lower energy excimer-like species then persists for >10 ns. Transient absorption experiments indicate that the majority of the excited-state population relaxes to the ground state on the 166 ps time scale, but a smaller fraction (<10%) survives in longer-lived trap or defect states. The rapid internal conversion leads to transient heating that results in a derivative line shape in the transient absorption signal at longer delays. DIP does not appear to support long-lived singlet exciton states or singlet fission. The implications of these results for the function of DIP in organic solar cells are discussed. ■ INTRODUCTIONOrganic molecular semiconductors are used in electronic devices ranging from transistors to solar cells. One advantage of organic semiconductors is the variety of molecular structures and interfaces that can give rise to different material properties. 1 The rylene family comprises a class of molecules that crystallize easily, have high stability, and support long exciton and charge carrier diffusion lengths. Diindenoperylene (DIP), whose structure is shown in Figure 1, is an extended rylene whose solid-state thin films have been extensively studied. 2−12 Its high degree of order, coupled with its excellent charge transport properties, have made it an increasingly popular choice as a component of organic photovoltaic (OPV) devices. 13−16 Furthermore, DIP has the ability to form crystalline mixtures with other conjugated molecules like perfluoropentacene or pentacene, opening up the possibility of making well-defined composite materials. 17−21 Despite its use in OPVs, much remains unclear in terms of DIP's basic photophysics. Since DIP's contribution to the photocurrent in an OPV should be determined at least in part by its exciton diffusion length, which in turn is determined by its excited-state lifetime, an improved understanding of its molecular photophysics is important for understanding how this material functions in an OPV.In this paper, we investigate the excited-state dynamics of DIP in both dilute solution and in a polycrystalline solid film at room temperature. In solution, DIP undergoes internal conversion back to the ground state on a subnanosecond time scale. This rapid internal conversion, seen in other acene molecules that incorporate a five-membered ring, has been attributed to a lack of resonance stabilization. 22,23 In solid form, DIP exhibits a complex decay that involves multiple emitting species. The time-resolved pho...

show abstract

Plasmon resonance modulated photoluminescence and Raman spectroscopy of diindenoperylene organic semiconductor thin film

Cited by 11 publications

References 20 publications

Crystalline versus Amorphous Donor-Acceptor Blends: Influence of Layer Morphology on the Charge-Transfer Density of States

Crystalline versus Amorphous Donor-Acceptor Blends: Influence of Layer Morphology on the Charge-Transfer Density of States

Quantification of energy losses in organic solar cells from temperature-dependent device characteristics

Excited-State Dynamics of Diindenoperylene in Liquid Solution and in Solid Films

Contact Info

Product

Resources

About