Light Harvesting for Organic Photovoltaics

Biohybrid Conjugated Polymer Materials for Augmenting Energy Conversion of Bioelectrochemical Systems

Bioelectrochemical systems (BESs) provide favorable opportunities for the sustainable conversion of energy from biological metabolism. Biological photovoltaics (BPVs) and microbial fuel cells (MFCs) respectively realize the conversion of renewable solar energy and bioenergy into electrical energy by utilizing electroactive biological extracellular electron transfer, however, along with this energy conversion progress, relatively poor durability and low output performance are challenges as well as opportunities. Advances in improving bio-electrode interface compatibility will help to solve the problem of insufficient performance and further have a far-reaching impact on the development of bioelectronics. Conjugated polymers (CPs) with specific optical and electrical properties (absorption and emission spectra, energy band structure and electrical conductivity) afforded by π-conjugated backbones are conducive to enhancing the electron generation and output capacity of electroactive organisms. Furthermore, the water solubility, functionality, biocompatibility and mechanical properties optimized through appropriate modification of side chain provide a more adaptive contact interface between biomaterials and electrodes. In this minireview, we summarize the prominent contributions of CPs in the aspect of augmenting the photovoltaic response of BPVs and power supply of MFCs, and specifically discussed the role of CPs with expectation to provide inspirations for the design of bioelectronic devices in the future.

Modelling the structural and reactivity landscapes of tucatinib with special reference to its wavefunction-dependent properties and screening for potential antiviral activity

HER-2 type breast cancer is one of the most aggressive malignancies found in women. Tucatinib is recently developed and approved as a potential medicine to fight this disease. In this manuscript, we present the gross structural features of this compound and its reactivity and wave function properties using computational simulations. Density functional theory was used to optimise the ground state geometry of the molecule and molecular docking was used to predict biological activity. As the electrons interact with electromagnetic radiations, electronic excitations between different energy levels are analysed in detail using time-dependent density functional theory. Various intermolecular and intermolecular interactions are analysed and reaction sites for attacking electrophiles and nucleophiles identified. Information entropy calculations show that the compound is inherently stable. Docking with COVID-19 proteins show docking score of − 9.42, − 8.93, − 8.45 and − 8.32 kcal/mol respectively indicating high interaction between the drug and proteins. Hence, this is an ideal candidate to study repurposing of existing drugs to combat the pandemic.

Light and electric field induced unusual large-scale charge separation in hybrid semiconductor objects

Separation of electric charges is the most crucial phenomenon in natural photosynthesis, and is also extremely important for many artificial energy conversion systems based on semiconductors. The usual roadblock in this context is the fast recombination of electrons and holes. Here we demonstrate that the synergy of light and electric fields allows separating very efficiently electric charges over an unusually large distance in TiO2. The generated internal electric field can also be used to shuttle electrons simultaneously to the two opposite sides of a hybrid TiO2-polyaniline object. This counterintuitive behavior is based on the combination of the principles of bipolar electrochemistry and semi-conductor physics.

Photoredox Organic Synthesis Employing Heterogeneous Photocatalysts with Emphasis on Halide Perovskite

Lately, heterogeneous semiconductor materials have been explored as an emerging type of efficient photocatalyst for photoredox organic synthesis. Among these semiconductors, lead halide perovskite materials demonstrate unique properties towards excellent charge separation and charge transfer, extremely long charge carrier migration, high efficiency in visible light absorption, and long excited states lifetimes, etc., as proved in ground-breaking solar cell applications, garnering necessary merits for an efficient catalytic system for photoredox organic reactions. Here, the latest progress in heterogeneous semiconductor materials towards this endeavor is examined, with particular emphasis on lead halide perovskite nanocrystals (NCs) in photocatalytic organic synthesis.

Directing charge transfer in perylene based light-harvesting antenna molecules

Directing energy and charge transfer processes in light-harvesting antenna systems is quintessential for optimizing the efficiency of molecular devices for artificial photosynthesis. In this work, we report a novel synthetic method to construct two regioisomeric antenna molecules (1-D2A2 and 7-D2A2), in which the 4-(n-butylamino)naphthalene monoimide energy and electron donor is attached to the perylene monoimide diester (PMIDE) acceptor at the 1- and 7-bay positions, respectively. The non-symmetric structure of PMIDE renders a polarized distribution of the frontier molecular orbitals along the long axis of this acceptor moiety, which differentiates the electron coupling between the donor, attached at either the 1- or the 7-position, and the acceptor. We demonstrate that directional control of the photo-driven charge transfer process has been obtained by engineering the molecular structure of the light-harvesting antenna molecules.

Spherical Supramolecular Structures Constructed via Chemically Symmetric Perylene Bisimides: Beyond Columnar Assembly

Like other discotic molecules, self-assembled supramolecular structures of perylene bisimides (PBIs) are commonly limited to columnar or lamellar structures due to their distinct π-conjugated scaffolds and unique rectangular shape of perylene cores. The discovery of PBIs with supramolecular structures beyond layers and columns may expand the scope of PBI-based materials. A series of unconventional spherical packing phases in PBIs, including A15 phase, σ phase, dodecagonal quasicrystalline (DQC) phase, and body-centered cubic (BCC) phase, is reported. A strategy involving functionalization of perylene core with several polyhedral oligomeric silsesquioxane (POSS) cages achieved spherical assemblies of PBIs, instead of columnar assemblies, due to the significantly increased steric hindrance at the periphery. This strategy may also be employed for the discovery of unconventional spherical assemblies in other related discotic molecules by the introduction of similar bulky functional groups at their periphery. An unusual inverse phase transition sequence from a BCC phase to a σ phase was observed by increasing annealing temperature.

Controlling Structure and Properties of Vapor-Deposited Glasses of Organic Semiconductors: Recent Advances and Challenges

The past decade has seen great progress in manipulating the structure of vapor-deposited glasses of organic semiconductors. Upon varying the substrate temperature during deposition, glasses with a wide range of density and molecular orientation can be prepared from a given molecule. We review recent studies that show the structure of vapor-deposited glasses can be tuned to significantly improve the external quantum efficiency and lifetime of organic light-emitting diodes (OLEDs). We highlight the ability of molecular simulations to reproduce experimentally observed structures, setting the stage for in silico design of vapor-deposited glasses in the coming decade. Finally, we identify research opportunities for improving the properties of organic semiconductors by controlling the structure of vapor-deposited glasses.

Guest-Responsive Reversible Electron Transfer in a Crystalline Porous Framework Supported by a Dynamic Building Node

We demonstrate a redox-active, crystalline donor-acceptor (D-A) assembly in which the electron transfer (ET) process can be reversibly switched. This ET process, induced by a guest-responsive structural transformation at room temperature, is realized in a porous, metal-organic framework (MOF), having anthracene (D)-naphthalenediimide (A) as struts. A control MOF structure obtained by a solvent-assisted linker exchange (SALE) method, replacing an acceptor strut with a neutral one, supported the switchable electronic states in the D-A MOF. Combined investigations with X-ray diffraction, spectroscopy, and theoretical analyses revealed the dynamic metal paddle-wheel node as a critical unit for controlling structural flexibility and the corresponding unprecedented ET process.

High-Performance Nonvolatile Organic Photonic Transistor Memory Devices using Conjugated Rod-Coil Materials as a Floating Gate

A novel approach for using conjugated rod-coil materials as a floating gate in the fabrication of nonvolatile photonic transistor memory devices, consisting of n-type Sol-PDI and p-type C10-DNTT, is presented. Sol-PDI and C10-DNTT are used as dual functions of charge-trapping (conjugated rod) and tunneling (insulating coil), while n-type BPE-PDI and p-type DNTT are employed as the corresponding transporting layers. By using the same conjugated rod in the memory layer and transporting channel with a self-assembled structure, both n-type and p-type memory devices exhibit a fast response, a high current contrast between "Photo-On" and "Electrical-Off" bistable states over 10⁵ , and an extremely low programing driving force of 0.1 V. The fabricated photon-driven memory devices exhibit a quick response to different wavelengths of light and a broadband light response that highlight their promising potential for light-recorder and synaptic device applications.

Watching Paint Dry: Operando Solvent Vapor Annealing of Organic Solar Cells

The commercialization of organic solar cell (OSC) technology will require highly reproducible techniques for controlling the morphology of bulk heterojunction blends. Variable-pressure solvent vapor annealing (VP-SVA) is one method for postprocessing organic solar cells with high precision; it can prevent the overannealing of cells that plagues conventional SVA processes. To gain insight into the dynamics of the VP-SVA process, we carried out operando measurements on OSCs with correlated in situ grazing-incidence wide-angle X-ray scattering (GIWAXS) measurements. We show that the partial pressure of solvent vapor controls the length scale of film reordering, with optimal restructuring taking place below the saturation vapor pressure of the solvent. The experiments reveal how the film crystallinity, domain sizes, and percolation pathways evolve over the course of the VP-SVA process and how subtle differences in these morphological parameters differentiate good OSCs from champion cells.

Enhanced Thermoelectric Performance of n-Type Organic Semiconductor via Electric Field Modulated Photo-Thermoelectric Effect

Modulating photophysical processes is a fundamental way for tuning performance of many organic devices. However, it has not been explored as an effective strategy to manipulate the thermoelectric (TE) conversion of organic semiconductors (OSCs) owing to their critical requirement to carrier concentration (>10¹⁸ cm^-3 ) and the fact of low exciton separation efficiency in single element OSCs. Here, an electric field modulated photo-thermoelectric (P-TE) effect in an n-type OSC is demonstrated to realize a significant improvement of TE performance. The electrical and spectroscopy characterizations reveal that the electric field gating generates combined modulation of exciton separation, charge screening, and carrier recombination, which produces a more than ten times improvement of photoinduced carrier concentration. These coupled processes contribute to the unconventional Seebeck coefficient (S)-electrical conductivity (σ) trade-off relationship of the photoexcited films, therefore leading to a more than 500% enhancement in the power factor for n-type OTE semiconductors. This work opens a unique way toward state-of-the-art organic P-TE materials for energy harvesting applications.

Crystal structure of 2,3-dimeth-oxy-meso-tetra-kis(penta-fluoro-phen-yl)morpholino-chlorin methyl-ene chloride 0.44-solvate

The title morpholino-chlorin, C46H16F20N4O3, was crystallized from hexa-ne/methyl-ene chloride as its 0.44 methyl-ene chloride solvate, C46H16F20N4O3·0.44CH2Cl2. The morpholino-chlorin was synthesized by stepwise oxygen insertion into a porphyrin using a 'breaking and mending strategy': NaIO4-induced diol cleavage of the corresponding 2,3-di-hydroxy-chlorin with in situ methanol-induced, acid-catalyzed intra-molecular ring closure of the inter-mediate secochlorins bis-aldehyde. Formally, one of the pyrrolic building blocks was thus replaced by a 2,3-di-meth-oxy-morpholine moiety. Like other morpholino-chlorins, the macrocycle of the title compound adopts a ruffled conformation, and the modulation of the porphyrinic π-system chromophore induces a red-shift of its optical spectrum compared to its corresponding chlorin analog. Packing in the crystal is governed by inter-actions involving the fluorine atoms of the penta-fluoro-phenyl substituents, dominated by C-H⋯F inter-actions, and augmented by short fluorine⋯fluorine contacts, C-F⋯π inter-actions, and one severely slipped π-stacking inter-action between two penta-fluoro-phenyl rings. The solvate methyl-ene chloride mol-ecule is disordered over two independent positions around an inversion center with occupancies of two × 0.241 (5) and two × 0.199 (4), for a total site occupancy of 88%.

Electrostatic Field-Induced Oscillator Strength Focusing in Molecules

The development of light-harvesting devices based on molecular materials depends critically on the ability to focus the electronic oscillator strength of molecules into the UV-vis spectral window. Typical molecular chromophores have only about 1% of their total electronic oscillator strength in this spectral region and thus perform at a small fraction of their possible effectiveness. This theoretical study finds that the electronic oscillator strength of polyenes in the UV-vis region may be enhanced by 1 order of magnitude using electrostatic fields, motivating specific experimental studies of oscillator strength focusing. We find scaling relationships between the polyene length, the intensity of the applied field, and the field-induced increase in oscillator strength that are useful for the implementation of light-harvesting strategies based on polyenes.

Using Dual Microresonant Cavity and Plasmonic Effects to Enhance the Photovoltaic Efficiency of Flexible Polymer Solar Cells

Fabricating polymer solar cells (PSCs) on flexible polymer substrates, instead of on hard glass, is attractive for implementing the advantage and uniqueness of the PSCs represented by mechanically rollable and light-weight natures. However, simultaneously achieving reliable robustness and high-power conversion efficiency (PCE) in such flexible PSCs is still technically challenging due to poor light harvesting of thin photoactive polymers. In this work, we report a facile, effective strategy for improving the light-harvesting performance of flexible PSCs without sacrificing rollability. Very high transparent (93.67% in 400–800 nm) and low sheet resistance (~10 Ω sq⁻¹) ZnO/Ag_(O)/ZnO electrodes were implemented as the flexible substrates. In systematically comparison with ZnO/Ag/ZnO electrodes, small amount of oxygen induced continuous metallic films with lower thickness, which resulted in higher transmittance and lower sheet resistance. To increase the light absorption of thin active layer (maintain the high rollability of active layer), a unique platform simultaneously utilizing both a transparent electrode configuration based on an ultrathin oxygen-doped Ag, Ag_(O), and film and plasmonic Ag@SiO₂ nanoparticles were designed for fully leveraging the advantages of duel microresonant cavity and plasmonic effects to enhance light absorbance in photoactive polymers. A combination of the ZnO/Ag_(O)/ZnO electrode and Ag@SiO₂ nanoparticles significantly increased the short-current density of PSCs to 17.98 mA cm⁻² with enhancing the photoluminescence of PTB7-Th film. The flexible PSC using the optimized configuration provided an average PCE of 8.04% for flexible PSCs, which was increased by 36.27% compared to that of the PSC merely using a conventional transparent indium tin oxide electrode.

Carbazole-based green and blue-BODIPY dyads and triads as donors for bulk heterojunction organic solar cells

Two BODIPY derivatives with one (B2) and two (B3) carbazole moieties were synthesized and applied as electron-donor materials in organic photovoltaic cells (OPV). Their optical and electrochemical properties were systematically investigated. These BODIPY dyes exhibit excellent solubility in organic solvents and present high molar extinction coefficients (1.37-1.48 × 10⁵ M^-1 cm^-1) in solutions with absorption maxima at 586 nm for mono-styryl groups and at 672 nm for di-styryl groups. The introduction of the styryl moieties results in a large bathochromic shift and a significant decrease in the HOMO-LUMO energy-gaps. The BODIPY dyes show relatively low HOMO energies ranging from -4.99 to -5.16 eV as determined from cyclic voltammetry measurements. Cyclic voltammetry measurements and theoretical calculations demonstrate that the frontier molecular orbital levels of these compounds match with those of PC₇₁BM as the acceptor, supporting their application as donor materials in solution-processed small molecule bulk heterojunction (BHJ) organic solar cells. After the optimization of the active layer, B2:PC₇₁BM and B3:PC₇₁BM based organic solar cells showed an overall power conversion efficiency of 6.41% and 7.47%, respectively. The higher PCE of the B3-based OSC is ascribed to the more balanced charge transport and exciton dissociation, better crystallinity and molecular packing.

Hybrid Lead-Halide Polyelectrolytes as Interfacial Electron Extraction Layers in Inverted Organic Solar Cells

A series of lead-halide based hybrid polyelectrolytes was prepared and used as interfacial layers in organic solar cells (OSCs) to explore their effect on the energy band structures and performance of OSCs. Nonconjugated polyelectrolytes based on ethoxylated polyethylenimine (PEIE) complexed with PbX2 (I, Br, and Cl) were prepared as polymeric analogs of the perovskite semiconductors CH3NH3PbX3. The organic/inorganic hybrid composites were deposited onto Indium tin oxide (ITO) substrates by solution processing, and ultraviolet photoelectron spectroscopy (UPS) measurements confirmed that the polyelectrolytes allowed the work function of the substrates to be controlled. In addition, X-ray photoelectron spectroscopy (XPS) results showed that Pb(II) halide complexes were present in the thin film and that the Pb halide species did not bond covalently with the cationic polymer and confirmed the absence of additional chemical bonds. The composite ratio of organic and inorganic materials was optimized to improve the performance of OSCs. When PbBr2 was complexed with the PEIE material, the efficiency increased up to 3.567% via improvements in open circuit voltage and fill factor from the control device (0.3%). These results demonstrate that lead-halide based polyelectrolytes constitute hybrid interfacial layers which provide a novel route to control device characteristics via variation of the lead halide composition.

π-Extension, Selenium Incorporation, and Trimerization: "Three in One" for Efficient Perylene Diimide Oligomer-Based Organic Solar Cells

Perylene diimide (PDI) and the vinylene-bridged helical PDI oligomers are versatile building blocks for constructing nonfullerene acceptors (NFAs). In this contribution, a benzene-cored star-shaped NFA, namely, TPDI2-Se, was designed and synthesized for organic solar cells (OSCs). The NFA with smaller π-conjugated blades, namely, TPDI-Se, was synthesized for comparison. Using the commercially available PTB7-Th as the electron donor, the best power conversion efficiency (PCE) of 3.62% was obtained for TPDI-Se-based OSCs. However, a much higher PCE of 8.59% was achieved for TPDI2-Se-based devices owing to the π-extension in the peripheral panels. Moreover, the photovoltaic performance of TPDI2-Se-based OSCs is also superior to those of the parent NFA TPDI2 (PCE of 7.84%)- and the blade moiety PDI2-Se (PCE of 6.61%)- based ones. Additionally, a remarkable short-circuit current (J_sc) value of 17.21 mA/cm² was obtained for TPDI2-Se-based OSCs, which is among the highest J_sc values reported in PDI-based OSCs. These results argue that the so-called "three in one" molecule design strategy of π-extension, selenium incorporation, and trimerization offers a robust approach to constructing high-performance PDI-based NFAs.

Photoinduced Betaine Generation for Efficient Photothermal Energy Conversion

The conversion of solar energy to thermal, chemical, or electrical energy attracts great attention in chemistry and physics. There has been a considerable effort for the efficient extraction of photons throughout the entire solar spectrum. In this work light energy was efficiently harvested by using a long-lived betaine photogenerated from an acridinium-based electron donor-acceptor dyad. The photothermal energy-conversion efficiency of the dyad is significantly enhanced by simultaneous illumination with blue (420-440 nm) and yellow (>480 nm) light in comparison with the sum of the conversion efficiencies for individual illumination with blue or yellow light. The enhanced photothermal effect is due to the photogenerated betaine, which absorbs longer-wavelength light than the dyad, and thus the dyad-betaine combination is promising for efficient photothermal energy conversion. The mechanisms of betaine generation and energy conversion are discussed on the basis of steady-state and transient spectral measurements.

Synthesis and Photophysical Study of [60]Fullerene-Maleimide Dyads

Novel [60]fullerene-maleimide dyads were synthesized by covalent linking of maleimide fluorophore to the [60]fullerene (C₆₀) via Bingel reaction. The dyads were well characterized and studied for their absorption and emission properties. The fluorescence quenching of maleimide moiety by C₆₀ was observed, indicating the intramolecular energy transfer from maleimide fluorophore to C₆₀ moiety.

Geminate recombination in organic photovoltaic blend PCDTBT/PC71BM studied by out-of-phase electron spin echo spectroscopy

The key process in organic solar cell operation is charge separation under light illumination. Due to the low dielectric constant of organic materials, the Coulomb attraction energy within the interfacial charge-transfer state (CTS) is larger than the thermal energy. Understanding the mechanism of charge separation at the organic donor/acceptor interface still remains a challenge and requires knowledge of the CTS temporal evolution. To address this problem, the CTS in the benchmark photovoltaic blend PCDTBT/PC₇₁BM was studied by the out-of-phase Electron Spin Echo (ESE). The protocol for determining the CTS geminate recombination rate for certain electron-hole distances was developed. Simulating the out-of-phase ESE trace for the CTS in the PCDTBT/PC₇₁BM blend allows precise determination of the electron-hole distance distribution function and its evolution with the increase in the delay after the laser flash. Distances of charge separation up to 6 nm were detected upon thermalization at a temperature of 20 K. Assuming the exponential decay of the recombination rate, the attenuation factor β = 0.08 Å^-1 is estimated for the PCDTBT/PC₇₁BM blend. Such a low attenuation factor is probably caused by a high degree of hole delocalization along the PCDTBT chain.

Revealing the Influences of Solvent Boiling Point and Alkyl Chains on the Adlayer Crystallinity of Furan-Diketopyrrolopyrrole-Thienylene Copolymer at Molecular Level

Crystallinity of the polymer poly(3,6-difuran-2-yl-2,5-di(2-octyldodecyl)-pyrrolo[3,4-c]pyrrole-1,4-dione-altthieylenevinylene) (PDVF) adlayers casted from low-boiling-point (L-bp), medium-bp (M-bp), and high-bp (H-bp) solvents was investigated through scanning tunneling microscopy (STM) and analyzed by the assistance of Hansen solubility parameter (HSP) theory and molecular dynamics (MD) simulations. Crystallinity of the PDVF adlayers increases evidently from the L- to H-bp solvents. Also, the solvent with an alkyl chain such as ethylbenzene (EB) facilitates in improving the crystallinity than the one without an alkyl chain such as chlorobenzene (CB) if the solvent bp is present in the same group. The HSP space discloses that EB is a marginal solvent for PDVF in contrast to CB. Quasi-isolate PDVF in the EB solution revealed by MD simulations facilitates the formation of crystallized domains through surface assembling mechanism. However, in CB, interconnected PDVF molecules through intermolecular overlapping tend to generate amorphous structures through direct deposition of the preformed structures in solution.

Facile C–H iodination of electron deficient benzodithiophene-S,S-tetraoxide for the development of n-type polymers

A C–H iodination reaction of the electron-poor building block, benzo[1,2-b:4,5-b0]-dithiophene-1,1,5,5-tetraoxide has been reported. This facile functionalization has led to the development of two novel n-type donor–acceptor conjugated polymers.

Can we utilize the higher Frenkel exciton state in biazulene diimides-based non-fullerene acceptors to promote charge separation at the donor/acceptor interface?

The pathway of charge transfer from the Frenkel exciton state of the acceptor to charge transfer states was investigated.

Global and target analysis of relaxation processes of the collapsed state of P3HT polymer nanoparticles

Organic–inorganic hetero-structures composed of P3HT PNPs and Au NPs have been designed for efficient light harvesting systems. Here electron transfer occurs from vibrationally hot S₁ state and delocalized collective state (CL_S) of PNPs to Au NPs.

Photoactive organic material discovery with combinatorial supramolecular assembly

Organic semiconductors have received substantial attention as active components in optoelectronic devices because of their processability and customizable properties. Tailoring the organic active layer in these devices to exhibit the desired optoelectronic properties requires understanding the complex and often subtle structure-property relationships governing their photophysical response to light. Both structural organization and molecular orbitals play pivotal roles, and their interactions with each other are difficult to anticipate based upon the structure of the components alone, especially in systems comprised of multiple components. In pursuit of design rules, there is a need to explore multicomponent systems combinatorially to access larger data sets, and supramolecularly to use error correcting, noncovalent assembly to achieve long-range order. This review will focus on the use of supramolecular chemistry to study combinatorial, hierarchical organic systems with emergent optoelectronic properties. Specifically, we will describe systems that undergo excited state deactivation by charge transfer (CT), singlet fission (SF), and Förster resonance energy transfer (FRET). Adopting combinatorial, supramolecular assembly to study emergent photophysics promises to rapidly accelerate progress in this research field.

Atomistic simulations of bulk heterojunctions to evaluate the structural and packing properties of new predicted donors in OPVs

Organic photovoltaic materials (OPVs), with low cost and structure flexibility, are of great interest and importance for their application in solar cell device development. However, the optimization of new OPV structures and the study of the structure arrangements and packing morphologies when materials are blended takes time and consumes raw materials, thus theoretical models could be of considerable value. In this work, we performed molecular dynamics simulations of present OPVs to understand the morphological packing of the donor-acceptor (DA) phases and DA heterojunction during evaporation and annealing processes, following inter and intramolecular properties like frontier orbitals, π-π stacking, coordination, distances, angles, and aggregation. Our considered donor molecules were selected from already proved experimental studies and also from predicted optimal compounds, designed through high throughput studies. The acceptor molecule employed in all our studied systems was PCBM ([6,6]-phenyl-C61-butyric acid methyl ester). Furthermore, we also analyze the influence of including different lateral aliphatic chains on the structural properties of the resulting DA packing morphologies. Our results can guide the design of new OPVs and subsequent studies applying charge transport and charge separation models.

Ultrafast Broadband Transient Absorption and Circular Dichroism Reveal Relaxation of a Chiral Copolymer

We present a study of the photoinduced dynamics of the chiral polyfluorene-phenylene copolymer PFPh in THF and in cholesteric thin films. After photoexcitation at 370 nm in THF, ultraviolet-visible-near-infrared (UV-vis-NIR) transient absorption spectra show fast subpicosecond to picosecond intrachain migration of singlet excitons, solvation dynamics, and an exciton lifetime of 410 ps. The PFPh thin film features also interchain singlet exciton migration and exhibits shorter (2.1 and 240 ps) and longer lifetime components (2800 ps, interchain recombination). Furthermore, a setup for ultrafast UV-vis broadband transient circular dichroism (TrCD) spectroscopy has been developed. Fast supramolecular relaxation processes are observed, which are linked to changes in the anisotropic polarizability and pitch length of the cholesteric film. Such combined ultrafast transient CD and absorption experiments hold promise to reveal not only details of relaxation processes in supramolecular arrangements but also structural rearrangements of chiral molecular systems featuring CD signals in the UV-vis region.