Red-shifted Absorption Research Articles

Sensitizer-Free Photochemical Regeneration of Benzimidazoline Organohydride.

Organohydrides are an important class of organic compounds that can provide hydride anions for chemical and biochemical reactions, as demonstrated by reduced nicotinamide adenine dinucleotides serving as important natural redox cofactors. The coupling of hydride transfer from the organohydride to the substrate and subsequent regeneration of the organohydride from its oxidized form can realize organohydride-catalyzed reduction reactions. Depending on the structure of the organohydride, its hydridicity and ease of regeneration vary. Benzimidazoline (BIH) is one of the strongest synthetic C-H hydride donors; however, its reductive regeneration requires highly reducing conditions. In this study, we synthesized various oxidized and reduced forms of BIH derivatives with aryl groups at the 2-position and investigated their photophysical and electrochemical properties. 4-(Dimethylamino)phenyl-substituted BIH exhibited salient red-shifted absorption compared with other synthesized BIH derivatives, and visible-light-driven regeneration without using an external photosensitizer was achieved. This knowledge has significant implications for the future development of solar-energy-based catalytic photoreduction technologies that utilize organohydride regeneration strategies.

Terminally Chlorinated and Thiophene-linked Acceptor-Donor-Acceptor Structured 3D Acceptors with Versatile Processability for High-efficiency Organic Solar Cells.

To exploit the potential of our newly developed three-dimensional (3D) dimerized acceptors, a series of chlorinated 3D acceptors (namely CH8-3/4/5) were reported by precisely tuning the position of chlorine (Cl) atom. The introduction of Cl atom in central unit affects the molecular conformation. Whereas, by replacing fluorinated terminal groups (CH8-3) with chlorinated terminal groups (CH8-4 and CH8-5), the red-shift absorption and enhanced crystallization are achieved. Benefiting from these, all devices received promising power conversion efficiencies (PCEs) over 16 % as well as decent thermal/photo-stabilities. Among them, PM6:CH8-4 based device yielded a best PCE of 17.58 %. Besides, the 3D merits with multi alkyl chains enable their versatile processability during the device preparation. Impressive PCEs of 17.27 % and 16.23 % could be achieved for non-halogen solvent processable devices prepared in glovebox and ambient, respectively. 2.88 cm2 modules also obtained PCEs over 13 % via spin-coating and blade-coating methods, respectively. These results are among the best performance of dimerized acceptors. The decent performance of CH8-4 on small-area devices, modules and non-halogen solvent-processed devices highlights the versatile processing capability of our 3D acceptors, as well as their potential applications in the future.

Near-infrared voltage-sensitive dyes based on chromene donor

Voltage-sensitive dyes (VSDs) are used to image electrical activity in cells and tissues with submillisecond time resolution. Most of these fast sensors are constructed from push-pull chromophores whose fluorescence spectra are modulated by the electric field across the cell membrane. It was found that the substitution of naphthalene with chromene produces a 60 to 80 nm red-shift in absorption and emission spectra while maintaining fluorescence quantum efficiency and voltage sensitivity. One dye was applied to ex vivo murine heart with excitation at 730 nm, by far the longest wavelength reported in voltage imaging. This VSD resolves cardiac action potentials in single trials with 12% ΔF/F per action potential. The well-separated excitation spectra between these long-wavelength VSDs and channelrhodopsin (ChR2) enabled monitoring of action potential propagation in ChR2 hearts without any perturbation of electrical dynamics. Importantly, by employing spatially localized optogenetic manipulation, action potential dynamics can be assessed in an all-optical fashion with no artifact related to optical cross-talk between the reporter and actuator. These new environmentally sensitive chromene-based chromophores are also likely to have applications outside voltage imaging.

Benzotriazole-based asymmetric nonfullerene acceptors with A-D-A1-A2 type structure for organic solar cells

Although the wide-bandgap benzotriazole (BTA)-based A2-A1-D-A1-A2 type nonfullerene acceptors (NFAs) have realized super-high open-circuit voltage (VOC) of 1.3 V, the short-circuit current density (JSC) of these materials lag behind the narrow-bandgap A-D-A type analogs. Here, we design and synthesize two asymmetric A-D-A1-A2 type molecules, A301 and A302, by adopting 1,1-dicyanomethylene-3-indanone (IC), BTA and 2-(1,1-dicyanomethylene)rhodanine (RCN) as A, A1 and A2 units, respectively. Under the synergistic regulation of asymmetric end groups and side chain engineering, A302 with alkyl side chains on D unit exhibits red-shifted absorption, tighter molecular packing, and stronger crystallinity in comparison with A301 with phenyl side chain. Consequently, PM6:A302-based organic solar cells (OSCs) realize an enhanced efficiency of 11.09% with an improved JSC of 17.95 mA cm−2, compared to those of PM6:A301-based device (PCE = 8.18%, JSC = 14.57 mA cm−2). Notably, the JSC of 17.95 mA cm−2 is the highest value for BTA-based NFAs to date. This work demonstrates A-D-A1-A2 type NFAs have great potential to balance the JSC and VOC, and side chain on D unit also has a great impact on the properties of this kind of materials.

Elucidating modelling of C≡N-based carbazole-arylamine hole transporting materials for efficient organic and perovskite solar cells

Recently, the scientific community has shown great interest in hole transport materials (HTMs) to develop efficient and stable organic and perovskite solar cells. To boost the photovoltaic performance of these solar cell devices, scientists have been investigating the use of modified HTMs. In this study, we have developed a distinctive and proficient approach to building a better photovoltaic material by modifying the endcaps of the reference (MA). Specifically, we designed five new efficient HTMs (MA1-MA5) through molecular engineering on a terminal of reference molecule MA. Using density functional theory (DFT) and time-dependent-DFT methods, we theoretically characterized the key characteristics of these newly designed materials, including the orientation of frontier molecular orbitals (FMO), absorption maxima, the partial density of states (PDOS), binding energies, reorganization energy, transition density matrix, fill factor (FF), open-circuit voltages (Voc) and power conversion efficiencies (PCEs) for these materials. Our theoretical representations revealed that newly constructed materials (MA1-MA5) have a highly red-shifted absorption spectrum with lower binding energies and narrow energy gaps, making them ideal for charge shifting. Among these designed MA1-MA5 materials, the MA1 has the potential to produce as much as higher 23.24% PCE when it will be used in fabricating solar cell devices, whereas, the other designed materials MA2-MA4 has also very comparable and much higher PCE values than the refence molecule MA. These findings demonstrate our efficient designing approach to tune the photovoltaic and optoelectronic properties of the HTMs, and we recommend these engineered materials for the future developments of an efficient solar cell devices.

Fabrication of Densely-Packed Janus Gold Nanoparticles Layer by Self-Assembly for a Potential Molecular Sensing Probe

Localized surface plasmon phenomena of metallic nanoparticles could be utilized for sensing applications. As the particles in the vicinity results in a near-field coupling phenomenon, a higher field enhancement factor increases the sensing sensitivity. In this research, we propose a self-assembled and closely-packed Janus gold nanoparticle (AuNP) structure for application in molecular sensing. We utilize three-phase interfacial trapping and Langmuir-Schaefer method for the fabrication of Janus AuNP layer. In our case, dodecylamine (DDA) was used as the analyte for sensing assay. We found that the color of our AuNP changes from red-wine to blue in conjunction with the phase changes from colloidal to closely-packed layer that results in a red-shift absorbance peak. In the application of sensing assay, the absorbance peak is revealed blue-shifted up to ~40 nm from pristine AuNP layer due to the adsorption of DDA on the particle surfaces. Sensitivity enhancement is also expected due to the hotspot arises from the plasmonic particles in vicinity. This research could be further developed to a sensitive and quantitative molecular sensor up to colorimetric specific biosensor.

NIR light-driven pure organic Janus-like nanoparticles for thermophoresis-enhanced photothermal therapy

Photothermal therapy (PTT) represents a promising noninvasive tumor therapeutic modality, but the current strategies for enhancing photothermal effect have been mainly based on promoting thermal relaxation or suppressing radiative dissipation process of excited energy, leaving little room for further improvement in photothermal effect. Herein, as a proof of concept, we report the thermophoresis-enhanced photothermal effect with pure organic Janus-like nanoparticles (Janus-like NPs) for PTT. The Janus-like NPs are eccentrically loaded with compactly J-aggregated photothermal molecules (DMA-BDTO), which show red-shifted absorption wavelength and inhibited radiative decay as compared to individual molecules. Under NIR irradiation, the asymmetric heat generation at particle surface endows Janus-like NPs the active thermophoresis, which further increases collisions and converts kinetic energy into thermal energy, and Janus-like NPs exhibit significantly elevated temperature as compared to conventional NPs with homogenously distributed DMA-BDTO. Both in vitro and in vivo results confirm such thermophoresis-enhanced photothermal effect for improved PTT. Our new strategy of thermophoresis-enhanced photothermal effect shall open new insights for improving photothermal-related tumor therapy.

Modeling of Conjugated Core-Based Non-Fullerene Acceptor Materials for Organic Photovoltaic Applications

Non-Fullerene acceptors (NFAs) are attracting much attention from scientists worldwide for their potential use in organic solar cells (OSC). Herein, we developed C-shaped NFAs acceptors (FA1–FA10) by performing end-capped alteration on GL1. The structural-property relation and optoelectronic characteristics were examined theoretically. Furthermore, the impact of structural changes on the optoelectronic characteristics of FA1–FA10 molecules was investigated by using density functional theory (DFT), and time-dependent DFT. The photo-physical and optoelectronic features such as frontier molecular orbitals, electron–hole overlapping, excitation and binding energy, molecular electrostatic potential, the density of states, transition density matrix, open circuit voltage, and reorganization energies of hole and electron, of the designed materials have been simulated. Compared to GL1 (R), the developed materials displayed a red-shifted absorption (ranges 769.84–856.36[Formula: see text]nm), better electric-charge movement, lower binding (0.30[Formula: see text]eV), and excitation energies (1.28[Formula: see text]eV), and narrower bandgaps (ranges 1.59–1.79[Formula: see text]eV), respectively. Therefore, we suggest these to synthetic researchers for the future development of efficient OSCs.

Double Dynamic Structural Change Enabling Tricolor Chromism by the Realization of Apparent Two-electron Transfer to Skip the Open-shell State.

Most redox systems generally cannot avoid the involvement of open-shell species upon generating multiply charged species, which often reduces reversibility in multi-color electrochromic systems. In this study, we newly synthesized octakis(aminophenyl)substituted pentacenebisquinodimethane (BQD) derivatives and their hybrids with alkoxyphenyl analogues. Thanks to apparent twoelectron transfer accompanied by double dramatic changes in the structure of the arylated quinodimethane skeleton, the dicationic and tetracationic states were generated and isolated quantitatively because of the negligible steady-state concentration of intermediary open-shell species such as monocation or trication radicals. When two electrophores with different donating abilities are attached to the BQD skeleton, a dicationic state with a different color can be isolated in addition to the neutral and tetracationic states. For the latter of these, an interchromophore interaction induces a red-shift of the NIR absorptions, thus realizing tricolor UV/Vis/NIR electrochromic behavior involving only closed-shell states.

Perylenemonoimide-subphthalocyanine derivatives: Synthesis, characterization and photovoltaic performance as non-fullerene acceptors in bulk heterojunction solar cells

Imide-based Subphthalocyanines (SubPcs) is gaining momentum as non-fullerene acceptors in organic solar cells (OSCs). Herein we report the synthesis, characterization, and photovoltaic performance of Perylenemonoimide (PMI)-SubPc conjugates in which the PMI is linked to the SubPc core by either alkynes or direct C-C bond. These derivatives are prepared via palladium-catalyzed cross-coupling reactions. The introduction of PMI units results in a red-shifted absorption, which can be described as the combination of the absorption properties of both SubPc and PMIs fragments. The absorption spectra are thus mainly composed of two transitions, one derived from the SubPc Q-band and the other from transitions within the PMI moieties. These PMI-SubPc systems exhibit moderate acceptor properties and therefore their use as non-fullerene acceptors in bulk-heterojunction organic solar cells is briefly explored.

Tetracyanobuta-1,3-diene (TCBD)-appended pyrrolopyrrole aza-BODIPYs as a panchromatic chromophore based on the push-pull strategy

Pyrrolopyrrole aza-BODIPY (PPAB), a dimeric BODIPY analogue containing a pyrrolopyrrole structure at the center, exhibits intense far-red and near-infrared (NIR) absorption and emission. Herein, tetracyanobuta-1,3-diene-appended PPABs (TCBD-PPABs) were synthesized by post-modification based on a [2+2] cycloaddition-retroelectrocyclization (CA-RE) reaction with tetracyanoethylene. Owing to the redshift of the PPAB absorption in the NIR region and the emergence of the intramolecular charge-transfer band in the visible region, TCBD-PPABs exhibit panchromatic absorption in the visible/NIR regions.

Baria-Silica Erbium-Doped Fibers for Extended L-Band Amplification

We present baria-silica erbium-doped fibers (Ba-EDF) for extending the bandwidth of L-band EDFAs beyond 1620 nm. Using a combination of modified chemical vapor deposition (MCVD) process and solution-doping technique, we demonstrate low loss (<10 dB/km at 1200 nm) fiber cores with BaO concentration of 1-3 mol% and Er <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3+</sup> concentration of 8×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">24</sup> m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> . We show that the optical properties and EDFA performance are positively affected by increasing the BaO content. Namely, when we increase the BaO concentration from 1.3 to 3 mol%, we observe a reduction of pair-induced quenching that correlates with a bi-exponential luminescence decay with a dominant 15.5 ms lifetime component. Furthermore, the slight modifications of absorption/ emission coefficients point to a red-shift of the signal excited state absorption and consequently, to a moderate extension of the L-band gain to longer wavelengths (1622 nm).

Regioselective Synthesis of Directly Connected BODIPY Dimers through Oxidative Coupling of α-Amino-Substituted BODIPYs.

A family of directly β,β-linked BODIPY dimers with amino groups at α-positions were regioselectively prepared by the oxidative coupling reaction of α-amino-substituted BODIPYs. The structure of one representative dimer was elucidated by X-ray diffraction analysis, showing its twisted orientation of two BODIPY units with a dihedral angle of 49°. Comparing with the corresponding monomers, these dimers showed red-shifted absorptions and emissions along with efficient intersystem crossing, giving ΦΔ of 43% for dimer 4b in toluene, indicating potential use as heavy-atom-free photosensitizers.

Effect of donor and π-spacer for non-linear optical property: Synthesis, photophysical studies, and Z-scan analysis

The impact of donor and π-spacer on linear and non-linear optical (NLO) properties was investigated by designing and synthesizing dyes having diethylamino coumarin and julolidine-based coumarin donors containing thiophene and phenyl-spacer with ethyl cyanoacrylate acceptor. Density functional theory (DFT), time-dependent DFT, and Z-scan methods were opted for this study. Diethylamino coumarin and julolidine-based coumarin dyes showed maximum absorption and emission in the range of 462–524 and 480–544, and 515–641 and 520–663 nm, respectively. A julolidine-based coumarin and thiophene spacer containing dye and diethylamino-based coumarin with phenyl spacer showed the most red-shifted and blue-shifted absorption and emission properties, respectively. All dyes showed considerable viscosity sensitivity in polar (PEG: ethanol) and non-polar (Paraffin: toluene) media. Also, the title dyes showed good thermal stability above 300 °C. Further, the theoretical investigation suggested dyes with julolidine-based coumarin and thiophene-spacer have better CT (through FMO, MEP, BLA, BOA, and QC calculations) λVert and hence showed superior linear and NLO properties in solvent phases. Lastly, the results obtained from the Z-scan method also showed similar results as revealed by the theoretical study.

Aggregation-induced structural symmetry breaking promotes charge separation for efficient photocatalytic hydrogen production.

Recently, organic semiconductors have received much attention in the field of photocatalysis due to their tunable physicochemical properties. However, organic semiconductor photocatalysts typically suffer from severe charge recombination due to high exciton binding energy. Herein, we found that aggregation of pyrene results in a red-shift of the light absorption from UV to visible light region. Importantly, the aggregation can induce dipole polarization by spontaneous structural symmetry breaking, thus significantly accelerating the separation and transfer of charge carriers. As a result, the pyrene aggregates display enhanced hydrogen photosynthesis activity. Furthermore, the noncovalent interactions allow for rational design of physicochemical and electronic properties of pyrene aggregates, further strengthening the charge separation and photocatalytic activity of aggregates. The quantum yield of pyrene aggregates for hydrogen production highly reaches 20.77% at 400 nm. Moreover, we have also observed pyrene analogues (1-hydroxypyrene, 1-nitropyrene and perylene) after aggregation all display large dipole moments induced by structural symmetry breaking and therefore accelerate the separation of charge carriers, confirming its general principle. This work highlights the achievement of using aggregation-induced structural symmetry breaking to enable the separation and transfer of charge carriers.

Unfused-ring acceptor based on a quinoxaline unit functionalized with meta-positioned alkoxy chains for efficient organic solar cells with high open-circuit voltage

Owing to the simple synthesis and flexible chemical modifiability of unfused-ring non-fullerene acceptors (UF-NFAs), they have gained great research attraction for fabricating organic solar cells (OSCs). However, UF-NFA-based devices still underperform fused-ring non-fullerene acceptor-based devices. Herein, a series of UF-NFAs based on a fluorinated quinoxaline (Qx) building block functionalized with meta-positioned alkoxy chains, namely FQxOC8-H, FQxOC8-F, and FQxOC8-Cl, are synthesized. Density-functional theory (DFT) calculations demonstrated that all UF-NFAs exhibited good backbone coplanarity, owing to the S⋯N and H⋯F nonbonding interactions. The resulting UF-NFAs showed broad absorption ranged from 500 to 900 nm as well as deep highest occupied molecular orbital (HOMO) levels. FQxOC8-Cl exhibited more red-shifted and greater absorption coefficient owing to the stronger molecular stacking caused by chlorine atoms of the end groups. Moreover, PM6:FQxOC8-Cl-based blended film exhibited reduced charge recombination, higher carrier mobilities, and suitable phase-separation domains. Accordingly, OSCs based on FQxOC8-Cl yielded a superior power conversion efficiency (PCE) of 10.52%. In contrast, FQxOC8-H-based device afforded a lower efficiency of 6.13%. Our work indicates that combining the fluorinated Qx motif functionalized with meta-positioned alkoxy chains with electron-withdrawing end-groups showed great potential to construct efficient UF-NFAs.

Synthesis of Near-Infrared-Absorbing Anionic Heptamethine Cyanine Dyes with Trifluoromethyl Groups.

A novel anionic heptamethine cyanine (HMC) dye with two trifluoromethyl groups that selectively absorb near-infrared light is synthesized. When contrasted with previously studied anionic HMC dyes with substituents such as methyl, phenyl, and pentafluorophenyl groups, the trifluoromethylated dye displays a red-shifted maximum absorption wavelength (for instance, 948 nm in CH2Cl2) along with enhanced photostability. Furthermore, HMC dyes with broad absorption in the near-infrared region are synthesized by combining a trifluoromethylated anionic HMC dye with a cationic HMC dye as a counterion.

G-C3N4-Co3O4 Z-Scheme Junction with Green-Synthesized ZnO Photocatalyst for Efficient Degradation of Methylene Blue in Aqueous Solution.

A simple wet chemical ultrasonic-assisted synthesis method was employed to prepare visible light-driven g-C3N4-ZnO-Co3O4 (GZC) heterojunction photocatalysts. X-ray diffraction (XRD), scanning electromicroscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), Brunauer-Emmett-Teller (BET), ultraviolet (UV), and electrochemical impedance spectroscopy (EIS) are used to characterize the prepared catalysts. XRD confirms the homogenous phase formation of g-C3N4, ZnO, and Co3O4, and the heterogeneous phase for the composites. The synthesized ZnO and Co3O4 by using cellulose as a template show a rod-like morphology. The specific surface area of the catalytic samples increases due to the cellulose template. The measurements of the energy band gap of a g-C3N4-ZnO-Co3O4 composite showed red-shifted optical absorption to the visible range. The photoluminescence (PL) intensity decreases due to the formation of heterojunction. The PL quenching and EIS result shows that the reduction of the recombination rate and interfacial resistance result in charge carrier kinetic improvement in the catalyst. The photocatalytic performance in the degradation of MB dye of the GZC-3 composite was about 8.2-, 3.3-, and 2.5-fold more than that of the g-C3N4, g-C3N4-ZnO, and g-C3N4-Co3O4 samples. The Mott-Schottky plots of the flat band edge position of g-C3N4, ZnO, Co3O4, and Z-scheme g-C3N4-ZnO-Co3O4 photocatalysts may be created. Based on the stability experiment, GZC-3 shows greater photocatalytic activity after four recycling cycles. As a result, the GZC composite is environmentally friendly and efficient photocatalyst and has the potential to consider in the treatment of dye-contaminated wastewater.

Understanding remarkably high triplet quantum yield in thione analogs of perylenediimide: A detailed theoretical study.

The diverse and tunable electronic structures of perylenediimide (PDI), together with its high thermal and chemical stability, make the compound suitable for applications in bioimaging, electrical, and optical devices. However, a large singlet-triplet gap (ΔES-T) and almost zero spin-orbit coupling (SOC) between the lowest excited singlet (S1) and triplet (T1) restrict intersystem crossing (ISC) in highly fluorescent pristine PDI, yielding a near zero triplet quantum yield (ΦT). Interestingly, a thione analogs of PDI with varied S content (mS-PDIs, m = 1-4) was experimentally shown to yield ΦT ∼ 1.0 through efficient ISC. Time-dependent optimally-tuned range-separated hybrid calculations are performed to rationalize the experimentally observed red-shifted optical absorption and also the remarkably high ISC with almost zero radiative fluorescence reported for these mS-PDIs. To this end, the relative energies of low-lying excited singlets Sn (n = 1, 2) and a few triplets Tn(n = 1-3), along with their nature (nπ* or ππ*), are assessed for each of the mS-PDIs studied in chloroform. To our surprise and contrary to the earlier reports, both S1 and T1 are found to be of the same ππ* character, originating from the highest occupied to lowest unoccupied orbital transition, which, therefore, leads to a still large ΔES-T and vanishingly small SOC, as expected from the identical wavefunction symmetry. Increasing S content lowers S1(ππ*) due to a greater extent of π-delocalization, which well complements and supports the observed red-shift. More importantly, the T2 (or T3) closely lying to the S1 is of nπ* and, therefore, produces a relatively smaller ΔES-T and larger SOC. Detailed kinetics analysis suggests S1(ππ*) → T2(nπ*) is the primary ISC channel for all mS-PDIs, which is responsible for the remarkably high ΦT observed. In addition, comparable SOC and ΔES-T produce similar ISC rates for all mS-PDIs.

Neutral outflows in high-z QSOs

The OH+(11 − 10) absorption line is a powerful tracer of inflowing and outflowing gas in the predominantly atomic diffuse and turbulent halo surrounding galaxies. In this Letter, we present observations of OH+(11 − 10), CO(9-8) and the underlying dust continuum in five strongly lensed z ∼ 2 − 4 quasi-stellar objects (QSOs), using the Atacama Large Millimeter/submillimeter Array (ALMA) to detect outflowing neutral gas. Blue-shifted OH+(11 − 10) absorption is detected in three out of five QSOs and tentatively detected in a fourth. Absorption at systemic velocities is also detected in one source also displaying blue-shifted absorption. OH+(11 − 10) emission is observed in three out of five QSOs at systemic velocities and the OH+(21 − 10) transition is also detected in one source. CO(9-8) is detected in all five QSOs at high S/N, providing information on the dense molecular gas within the host galaxy. We compare our sample to high-z far-infrared (FIR) luminous star-forming and active galaxies from the literature. We find no difference in OH+ absorption line properties between active and star-forming galaxies with both samples roughly following the same optical depth-dust temperature relation. This suggests that these observables are driven by the same mechanism in both samples. Similarly, star-forming and active galaxies both follow the same OH+ emission–FIR relation. Obscured QSOs display broader (&gt; 800 km s−1) emission than the unobscured QSOs and all but one of the high-z star-forming galaxies (likely caused by the warm molecular gas reservoir obscuring the accreting nucleus). Broader CO(9-8) emission (&gt; 500 km s−1) is found in obscured versus unobscured QSOs, but overall they cover a similar range in line widths as the star-forming galaxies and follow the CO(9-8)–FIR luminosity relation found in low-z galaxies. We find that outflows traced by OH+ are only detected in extreme star-forming galaxies (indicated by broad CO(9-8) emission) and in both types of QSOs, which, in turn, display no red-shifted absorption. This suggests that diffuse neutral outflows in galaxy halos may be associated with the most energetic evolutionary phases leading up to and following the obscured QSO phase.