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Non-toxic molecular ferroelectrics have attracted significant interest due to their unique flexibility, low costs, and environmental friendliness. However, such materials with narrow bandgaps and ferroelectricity above room temperature (RT) are still scarce. Herein, we present a brand-new lead-free molecular ferroelectric [C8N2H22]1.5[Bi2I9] synthesized hydrothermally. [C8N2H22]1.5[Bi2I9] features a zero-dimensional (0D) structure with a polar space group of Pc, as confirmed by single-crystal X-ray diffraction and second-harmonic generation (SHG) analyses. The RT hysteresis loop reveals the intrinsic ferroelectricity of [C8N2H22]1.5[Bi2I9] with a spontaneous polarization (Ps) of 1.3 μC cm−2. A visible-light optical bandgap has been confirmed by UV-vis spectroscopy and theoretical calculations. A notable ferroelectric photovoltaic (PV) effect has been revealed in [C8N2H22]1.5[Bi2I9]-based photoelectric devices with an open-circuit voltage (Voc) of 0.39 V and a short-circuit current density (Jsc) of 2.3 μA cm−2 under AM 1.5G illumination. The PV performance can be significantly enhanced by tuning the ferroelectric polarization, achieving a maximum Voc of 0.47 V and Jsc of about 50 μA cm−2. This study offers a novel member of the 0D lead-free hybrid organic–inorganic molecular ferroelectric family possessing great promise for optoelectronic devices. [ABSTRACT FROM AUTHOR]

Non-toxic molecular ferroelectrics have attracted significant interest due to their unique flexibility, low costs, and environmental friendliness. However, such materials with narrow bandgaps and ferroelectricity above room temperature (RT) are still scarce. Herein, we present a brand-new lead-free molecular ferroelectric [C8N2H22]1.5[Bi2I9] synthesized hydrothermally. [C8N2H22]1.5[Bi2I9] features a zero-dimensional (0D) structure with a polar space group of Pc, as confirmed by single-crystal X-ray diffraction and second-harmonic generation (SHG) analyses. The RT hysteresis loop reveals the intrinsic ferroelectricity of [C8N2H22]1.5[Bi2I9] with a spontaneous polarization (Ps) of 1.3 μC cm−2. A visible-light optical bandgap has been confirmed by UV-vis spectroscopy and theoretical calculations. A notable ferroelectric photovoltaic (PV) effect has been revealed in [C8N2H22]1.5[Bi2I9]-based photoelectric devices with an open-circuit voltage (Voc) of 0.39 V and a short-circuit current density (Jsc) of 2.3 μA cm−2 under AM 1.5G illumination. The PV performance can be significantly enhanced by tuning the ferroelectric polarization, achieving a maximum Voc of 0.47 V and Jsc of about 50 μA cm−2. This study offers a novel member of the 0D lead-free hybrid organic–inorganic molecular ferroelectric family possessing great promise for optoelectronic devices. [ABSTRACT FROM AUTHOR]

Organic solar cells (OSCs) based on non-fused ring electron acceptors (NFREAs) have shown significant potential for practical application owing to their easily tunable chemical structures and short synthesis routes. The merging of side-chain engineering and terminal-group halogenation has facilitated the optimization of NFREAs properties. Thus, in this study, we developed four NFREAs using a naphthalenediimide (NDI) unit with different alkyl side-chains (–C6C10 or –C8C12) as the building block and two different electron-withdrawing groups 2-(3-oxo-2,3-dihydro-1H-inden-1-ylidene) malononitrile (IC) and chlorinated IC (IC-2Cl) as the terminal groups. These NFREAs were designated as NDI610-H, NDI610-Cl, NDI812-H, and NDI812-Cl, respectively. All four NFREAs exhibited similar optical bandgaps and molecular conformations. Under the synergistic effects of side-chain modification and terminal-group halogenation, the NFREAs-based active-layer morphologies were significantly different. The NDI610-Cl-based blended film demonstrated favorable phase-separation morphology, facilitating exciton dissociation and charge transport in the corresponding OSCs. Thus, the PM6:NDI610-Cl-based OSCs achieved a maximum power conversion efficiency (PCE) of 8.35%. Moreover, using D18 as the polymer donor further enhanced the device performance, with the D18:NDI610-Cl-based device yielding a higher PCE of 10.25% due to improved short-circuit current and fill factor. Our findings indicate that selecting an NDI unit as the building block and combining tailored alkyl side-chains with altered terminal groups are promising strategies for constructing highly efficient NFREAs. [ABSTRACT FROM AUTHOR]

Transparent TiO2 photoanodes offer promise for new solar technology due to their high light transmittance, but the persistently inadequate solar conversion efficiency continues to pose obstacles for practical application. This research utilized n-butyl titanate and black P25 TiO2 (B-P25) to construct transparent TiO2 photoanodes for quantum dot sensitized solar cells (QDSSCs). The B-P25 presents rich oxygen vacancies after reduction, along with the generation of more pore structures in the TiO2 photoanode films, facilitating the transport of photogenerated charge carriers in the photoanode films. Therefore, the photoelectric conversion efficiency (PCE) is significantly enhanced from 1.77% to 5.04%, with an increase in the short-circuit current density in the J–V curve from 8.10 to 17.67 mA cm−2. This study demonstrates that B-P25 prepared using the reduction method can effectively fabricate photoanodes with high photovoltaic performance, which improves the optical properties and solar cell efficiency of QDSSCs. [ABSTRACT FROM AUTHOR]

Three new d8- and d10-configuration based 1,1′-bis-(diphenylphosphino)ferrocene (dppf) appended thiosquarates complexes with general composition [M(mtsq)2dppf] (M = Ni2+ (NiL2); Zn2+ (ZnL2) and Cd2+ (CdL2)) (mtsq = 3-ethoxycyclobutenedione-4-thiolate) have been synthesized and characterized spectroscopically as well as in case of NiL2 by single crystal X-ray diffraction technique. The single crystal X-ray analysis reveals square planar geometry around Ni(II) in NiL2, where Ni(II) coordinates with two sulfur centres of two mtsq ligands in monodentate fashion and two phosphorus of a dppf ligand in chelating mode. The supramolecular architecture of NiL2 is sustained by intermolecular C–H⋯O interactions to form one-dimensional chain. Further, the application of these newly synthesized complexes as sensitizers and co-sensitizers/co-absorbents with ruthenium based N719 sensitizer in dye-sensitized solar cells (DSSCs) have been explored. The DSSC set-up based on NiL2 offers best photovoltaic performance with photovoltaic efficiency (η) 5.12%, short-circuit current (Jsc) 11.60 mA cm−2, open circuit potential (Voc) 0.690 V and incident photon to current conversion efficiency (IPCE) 63%. In co-sensitized DSSC set-up, ZnL2 along with state-of-the-art N719 dye displays best photovoltaic performance with η 6.65%, Jsc 14.47 mA cm−2, Voc 0.729 V and IPCE 69%, thereby showing an improvement by 15.25% in photovoltaic efficiency in comparison to the photovoltaic efficiency of N719 sensitized DSSC set-up. Variation in co-sensitization behaviour have been ascribed to the differences in the excited state energy level of co-sensitizers. The ZnL2 and CdL2 have a higher energy level position than N719 dye, allowing efficient electron transfer to N719 during light irradiation, while excited state of NiL2 is lower than N719 dye, preventing photoexcited electron transfer to N719, resulting in its lowest overall efficiency among the three co-sensitized DSSC setups. [ABSTRACT FROM AUTHOR]

Hybrid halide two dimensional (2D) perovskites have attracted considerable attention because they exhibit an improvement in perovskite solar cells compared with their 3D analogs. However, their bulky organic space group, leading to higher bandgaps and exciton binding energy, limits the charge transport in solar cells. Herein, the 3-(aminomethyl)pyridinium (3API2, C6H10N2I2) dication is incorporated into FA(Pb0.5Sn0.5)I3 to develop zigzag type 2D Dion–Jacobson-phase perovskites, which have low band gaps in the range of 1.44 to 1.53 eV for concentrations from 5 mol% to 20 mol% due to structural distortion. The introduction of the 3API2 cation increases the carrier conductivity and produces a high-quality perovskite film with no pinhole and connected grains, which is favorable for efficient carrier transport. Consequently, solar cells employing FA(Pb0.5Sn0.5)I3 with 10 mol% 3API2 added as a light absorber achieve a power conversion efficiency of 5.46% with an open-circuit voltage of 0.47 V, a fill factor of 58.07% and a short-circuit current density of 20.18 mA cm−2. With this class of new 2D Dion–Jacobson perovskite compositions, this work suggests potential future directions for improving the performance and device stability of perovskite solar cells. [ABSTRACT FROM AUTHOR]

Solar-driven interfacial evaporation is increasingly used in desalination due to its excellent evaporation performance. The continuous evaporation of water would lead to an increase in the salinity of the evaporator, which has been often neglected and rarely exploited. In this work, a calcium alginate hydrogel and nickel foam composited membrane (CHN) was proposed as a new platform for constructing solar-powered hybrid systems with the function of synchronous desalination and salinity power generation. The calcium alginate hydrogels can reduce the enthalpy of water evaporation and convert the salinity gradient between the evaporator and seawater into electrical energy. The evaporation rate of the mixed system (CHN-CB) with carbon black (CB) as the solar absorber is greater than 2.1 kg m−2 h−1. Additionally, under 1 sun, the system achieved a maximum short-circuit current of 20.3 mA m−2 and generated an extra electrical power of 5.3 mW m−2. As a universal multi-energy conversion platform, the CHN membranes can combine different photothermal materials for synchronous evaporation and salinity gradient power generation. These results open new paths for the combination of desalination and power generation, demonstrating the potential for diversified use of blue energy. [ABSTRACT FROM AUTHOR]

A photo-driven self-powered aptasensor was constructed based on a matching capacitor and the ZnIn2S4/Ti3C2 heterojunction as the photoanode and Cu2O as the photocathode in a dual-photoelectrode sensing matrix for multiple signal amplification for the ultrasensitive detection of microcystin-RR (MC-RR). The introduction of Ti3C2 MXene nanosheets on the photoanode surface can not only accelerate the transfer and separation of photoinduced electron/hole pairs, thus enhancing the output signal of the photo-driven self-powered system, but also provide a larger specific surface area for the immobilization of the bio-recognition unit aptamer. More importantly, for a portable and miniaturized device, a micro-workstation with the size of a universal serial bus (USB) disk and a novel short-circuit current access was proposed to capture the instantaneous output electrical signal for real-time data tracking. In such a way, a sensitivity of 2.7 mA pM−1 was achieved when the matching capacitor was integrated into the self-powered system, which was 22 times that without a capacitor. After the interaction between MC-RR and the corresponding aptamer, a 'signal-off' detection configuration was formed via the steric hindrance effect. Therefore, such a multiple signal amplification system realized the ultrasensitive and selective determination of MC-RR successfully. Under optimal conditions, the linear range of the self-powered aptasensor was 0.1 to 100 pM and the detection limit was 0.033 pM (S/N = 3). The aptasensor was applied to the detection of MC-RR in fish, exhibiting good reproducibility (≈3.88%), paving the way for detecting microcystins in real-life samples. [ABSTRACT FROM AUTHOR]

New stable frictional materials based on metal–organic frameworks (MOFs) are greatly desired for applications in self-powered systems. This work reports an ionic MOF material with efficient charge separation mediated by charge induction. ZUT-iMOF-1(Cu) is chemically stable and its triboelectric output performance surpasses those of traditional MOF materials. The short-circuit current of the iMOF triboelectric nanogenerator is 73.79 μA at 5 Hz. The output performance remains stable over 50 000 cycles of continuous operation. The charge and power densities peak at 123.20 μC m−2 and 3133.23 mW m−2. Owing to its high output performance, ZUT-iMOF-1(Cu) effectively prevents metal corrosion in cathodic-protection systems. Theoretical calculations show that increasing the charge-separation effect promotes the frictional electricity generation behaviour. This study provides research suggestions for ionic MOF frictional materials and will promote their application in self-powered electrochemical cathodic-protection systems. [ABSTRACT FROM AUTHOR]

A set of ullazine-derived D–π–A–π–A photosensitisers were considered and selected for a potential dye with the best performance via computational approaches. The designed dyes HJ1–HJ13, which originated from dye YZ7, were constructed with different π-linking motifs and two kinds of auxiliary withdrawing groups. The photoelectric and photovoltaic parameters were determined by density functional theory approaches, and PBE0 optimisation with the TD-cam-B3LYP method was shown to be the best choice of functional in these designed dyes, with the calculated maximum absorption wavelength and excited lifetime in accordance with the experimental findings for YZ7. Replacement of the C≡C bond by the C＝C bond could reduce aggregation and improve the photoelectronic property. In addition, the D–π–A–π–A-type photosensitiser was found to achieve higher light-harvesting efficiency and higher performance for dye-sensitised solar cells (DSSCs). HJ8 was selected as the potential dye for DSSCs, as it had a 69 nm redshift in the maximum absorption wavelength and a 66% increment in the maximum extinction coefficient compared to YZ7, and achieved 99.9% light-harvesting efficiency, the longest excited time of 2.82 ns, a suitable driving force of injection and regeneration, the largest short-circuit current density and the largest open-circuit voltage. Our theoretical results provide strong guidance for discovering new efficient D–π–A–π–A-type organic dyes in DSSCs. [ABSTRACT FROM AUTHOR]

ITIC-series nonfullerene organic photovoltaics (NF OPVs) have realized the simultaneous increases of the short-circuit current density (JSC) and open-circuit voltage (VOC), called the positive correlation between JSC and VOC, which could improve the power conversion efficiency (PCE). However, it is complicated to predict the formation of positive correlation in devices through simple calculations of single molecules due to their dimensional differences. Here, a series of symmetrical NF acceptors blended with the PBDB-T donor were chosen to establish an association framework between the molecular modification strategy and positive correlation. It can be found that the positive correlation is modification site-dependent following the energy variation at the different levels. Furthermore, to illustrate a positive correlation, the energy gap differences (ΔEg) and the energy level differences of the lowest unoccupied molecular orbitals (ΔELUMO) between the two changed acceptors were proposed as two molecular descriptors. Combined with the machine learning model, the accuracy of the proposed descriptor is more than 70% for predicting the correlation, which verifies the reliability of the prediction model. This work establishes the relative relationship between two molecular descriptors with different molecular modification sites and realizes the prediction of the trend of efficiency. Therefore, future research should focus on the simultaneous enhancement of photovoltaic parameters for high-performance NF OPVs. [ABSTRACT FROM AUTHOR]

Inspired by the reference R with the IUPAC name ((Z)-2-(aminomethyl)-3-(5-((3-methyl-5-(7-(4-methyl-5-(5,10,15-trimethyl-10,15-dihydro-5H-diindolo[3,2-a:3′,2′-c]carbazol-3-yl)thiophen-2-yl)benzo[c][1,2,5]thiadiazol-4-yl)thiophen-2-yl)ethynyl)furan-2-yl)acrylic acid)), six new organic (D–π–A) dyes for dye-sensitized solar cell (DSSC) applications have been designed. The designed molecules have an electron donor (D), triazatruxene, connected through different π-bridges and an electron acceptor (A), 2-cyanoacrylic acid. The key parameters of the optoelectronic and photoelectric performances were computed by density functional theory (DFT) and time-dependent density functional theory (TD-DFT). Compared to the original dye R, the designed compounds have a higher light harvesting ability with an absorption spectrum that appeared around the infrared region. The maximum absorption wavelength shifted to red from 78 nm to 148 nm, and the light-harvesting efficiency (LHE) curve broadened in the visible region and excellent electron injection efficiency was observed. All these contribute to better short-circuit current density (JSC) and power conversion efficiency (PCE). The results obtained through the global evaluation model for the reference dye R were JSC = 19.21 mA cm−2, VOC = 0.838 V, and PCE = 13.92%. These values are closer to the experimental results (JSC = 19.74 mA cm−2, VOC = 0.957 V, and PCE = 13.4%). The Tat-2 dye achieved a PCE of 23.75%. Therefore, it can be considered a candidate dye for high-yield DSSCs. [ABSTRACT FROM AUTHOR]

In this work, we present the potassium niobate (KNbO3) nanoparticles as a suitable mesoporous photoelectrode for dye-sensitized solar cells (DSSCs). The KNbO3 particles were synthesized by the microwave-assisted hydrothermal method using mild conditions and characterized by SEM, XRD, Raman, and UV-Vis diffuse reflectance. The particles presented a pyramidal tower-like shape with an orthorhombic structure and an indirect bandgap of (3.0 ± 0.1) eV. Dye-sensitized solar cells were assembled using the synthesized KNbO3 nanoparticles, which were deposited as a photoelectrode on a TiO2 recombination charge blocking layer. It is noticeable that the synergistic operation of the TiO2 blocking layer and KNbO3 photoelectrode is essential to achieve photovoltaic behaviour in our solar cells. The short-circuit current density of Jsc = 2.82 mA, open-circuit voltage Voc = 669 mV, fill factor FF = 0.62, and a power conversion efficiency PCE = 1.17%, reports elevated parameters if compared to other DSSCs alternative materials, becoming potassium niobate suitable as photoelectrode. [ABSTRACT FROM AUTHOR]

Multistage amorphous materials have promising applications in the catalytic performance of dye-sensitized solar cells (DSSCs). Herein, an amorphous sheet–raspberry sandwich-like ZnCo2S4@MnCo2S4/CP composite material was rationally designed and developed as a counter electrode (CE) for DSSCs by applying a three-step hydrothermal method. The first development of the amorphous composites as CEs resulted in lower charge transfer resistance at the CE/electrolyte interface and improved the fill factor and short-circuit current density. The excellent catalytic performance is mainly attributed to the large number of unsaturated coordination sites generated by the undirected structure of the lamellar–raspberry intercalated amorphous material, the smooth ion transport interface with a self-built corrosion-resistant layer, coupled with the dual catalytic performance of the Zn, Co, and Mn composites, and the good electrical conductivity of the C substrate. When ZnCo2S4@MnCo2S4/CP was used as the CE on a Ti substrate, the photoelectric conversion efficiency was as high as 11.68% (Voc = 0.821, Jsc = 20.14 mA cm−2, and FF = 0.71) under 100 mW cm−2 light illumination. This paper provides a design idea for amorphous materials in terms of catalytic performance and a method for developing alternatives to Pt electrodes. [ABSTRACT FROM AUTHOR]

Two small molecule (SM) donors, named CBTSeHR and CBTSeEHR, have been constructed by introducing selenophenes and chlorine atoms simultaneously into the conventional benzodithiophene–terthiophene–rhodanine architecture. In comparison with the non-chlorinated and thiophene based counterpart, the new SM donors exhibit a red-shifted absorption band, lower highest occupied molecular orbital (HOMO) energy levels, stronger intermolecular packing and higher molecular crystallinity. When combined with non-fullerene molecule FO-2Cl, the optimized all-small-molecule organic solar cells (ASM-OSCs) based on CBTSeEHR give a moderate power conversion efficiency (PCE) of 9.30%. Notably, CBTSeHR based devices achieve an outstanding performance of 12.10% with a high open-circuit voltage (Voc) of 0.881 V, short-circuit current densities (Jsc) of 18.76 mA cm−2 and fill factor (FF) of 0.732, benefiting from the deep HOMO level, good light-harvesting ability and favorable morphology in the active layer. These findings provide an effective strategy to develop the medium band-gap SM donors for high-performance ASM-OSCs. [ABSTRACT FROM AUTHOR]

As a new energy-harvesting and signal-monitoring technology, triboelectric nanogenerators (TENGs) have received increasing attention. Research into the output performance is essential to promote the application of TENGs. Based on copper meshes with an in situ-grown conical nanoneedle (IGCN) structure on the surface, a poly(β-hydroxybutyrate) (PHB) membrane was hot embossed to construct a microstructure. Then, the effects of the copper mesh hot-embossing on the microstructures, hydrophilic and hydrophobic properties, and the mechanical properties of the PHB membrane were investigated. A TENG was made by a hot-embossed PHB membrane and expanded polytetrafluoroethylene (ePTFE), and the influence of the microstructures on the triboelectric properties was explored. The results showed that the surface roughness of the PHB membrane was significantly increased by the hot embossing, and the roughness increased with the increase in the copper mesh size. Compared with the smooth copper mesh hot-embossing, the roughness of the PHB membrane hot embossed with IGCN was increased more obviously. The introduction of IGCN could significantly improve the output performance of TENG. Compared with using the original PHB membrane, the open-circuit voltage, short-circuit current density, and short-circuit transferred charge density of the TENG using the PHB membrane hot-embossed with copper mesh with a 500 mesh number with nanoneedles were increased by 86.6%, 54.8%, and 96.7%, respectively, which provides a new method to improve the output performance of TENGs. [ABSTRACT FROM AUTHOR]

With the increasing popularity of artificial intelligence, wearable and functional fabric triboelectric nanogenerators (F-TENGs) have an increasingly prominent role in human activities. Here, a new self-powered fabric composition detection system with high sensitivity and responsivity has been developed from F-TENGs modified by different functional groups. The power unit and group analysis system were successfully integrated into one device. Groups with different electronegativity were grafted onto the silk surface, and this silk was applied as the friction electrode to assemble TENG devices. The TENG with the original silk electrode exhibits a stable output performance with a short-circuit current of 11.8 μA and an output voltage of 49.8 V, while the corresponding short-circuit current and output voltage would gradually decrease with the increase of electronegativity for the grafted groups. This variation trend has resulted from different contributions of different functional groups to contact electrification of silks. Meanwhile, the group analysis system exhibits good sensitivity and selectivity for common functional groups with different electronegativity. This work provides a novel strategy to fabricate the fabric composition analysis system, which possesses tremendous application potential to collect human motion energy for detecting group types without any additional power supplies. [ABSTRACT FROM AUTHOR]

In this paper, a new small-molecule donor with a fluorinated benzodithiophene core and rhodanine analogue end groups, named BTEHR-FT, has been designed and synthesized, which has excellent solubility and thermal stability for solution-processed device fabrication. Moreover, BTEHR-FT shows a low-lying highest occupied molecular orbital (HOMO) energy level of -5.45 eV due to the introduction of fluorine atoms. When blended with a nonfullerene acceptor F-2Cl, the BTEHR-FT based all-smallmolecule organic solar cell (ASM-OSC) exhibits a high open-circuit voltage (Voc) of 0.948 V as expected, but a low short-circuit current density (Jsc) of 12.10 mA cm-2 and fill factor (FF) of 0.658 due to the bad morphology of the active layer, giving a moderate power conversion efficiency (PCE) of 7.55%. After thermal annealing treatment, a promising PCE of 10.71% was obtained benefiting from the great enhancement of Jsc (16.59 mA cm-2) and FF (0.693), which is among the highest values for non-Y series acceptor-based ASM-OSCs reported to date. This work provides a guideline for the design of smallmolecule donors for efficient organic solar cells. [ABSTRACT FROM AUTHOR]

CdSSe alloy and CdS/CdSe core/shell quantum dots (QDs) are widely studied in quantum dot solar cells (QDSSCs). However, to date, there have been no detailed comparative investigations into the cell performance between CdSSe alloy and CdS/CdSe core/shell structures prepared with the same preparation process. In this work, the performances of CdSSe alloy and CdS/CdSe core/shell QDSSCs, which are prepared with the same SILAR (successive ionic layer adsorption and reactions) process, are investigated in detail. By simply tuning the layer numbers and arrangement sequence of the CdS and CdSe layers, a series of QDs, including CdSSe alloy structures, CdS/CdSe multilayer structures, and CdS/CdSe core/shell structures, are successfully prepared with a layer-by-layer technique, while maintaining a similar morphology. Based on these QD sensitized TiO2 photoanodes, QDSSCs are assembled. The CdS/CdSe core/shell QDSSCs yield a maximum power conversion efficiency of 5.08% under AM 1.5 illumination of 100 mW cm−2, which is increased by 77% in comparison with that of CdSSe alloy QDSSCs (2.87%). The significantly enhanced photovoltaic performance of QDSSCs with core/shell architectures is mainly attributed to their high short-circuit current density, which arises from the enhanced absorption intensity. In addition, the CdS/CdSe core–shell contributes to the attenuation of the interfacial charge recombination rate and prolongs the electron lifetime, resulting in more efficient charge collection in QDSSCs. [ABSTRACT FROM AUTHOR]

The synthesis, characterisation and photovoltaic performance of an indacenodithiophene (IDT)-based organic dye in DSSCs has been presented. The dye was designed with a novel A–D–A system, which combines the advantages of a large, π-extended donor core, flanked with double acceptor/anchoring groups. The studies presented herein illustrate the utility of the IDT core as an efficient energy-level mediator, and fluorescence resonance energy-transfer module operating via intramolecular charge transfer (ITC). In contrast to the current dyes used for DSCCs, the excitation in the IDT moiety occurs symmetrically along the long axis of the molecule, representing a new pathway of development of DSSCs. This compact system when fabricated into a metal free dye sensitized solar cell achieves promising power conversion efficiency of up to 4.2%, with a high short-circuit current density (Jsc) of 11.69 mA cm−2 and open-circuit voltage (Voc) of 0.6 V and fill factor (FF) of 0.6 under AM 1.5 irradiation (100 mW cm2). [ABSTRACT FROM AUTHOR]

Four tetraphenylethylene-bridged X-shaped photosensitizers JY66–69 containing one triphenylamine (TPA) donor and another donor TPA, carbazole, phenothiazine or dithieno[3,2-b:2′,3′-d]pyrrole (DTP) as the neighboring donor were designed and applied in dye-sensitized solar cells. Compared with the symmetrical twin TPA-based dye JY66, the introduction of carbazole or phenothiazine neighboring donor (JY67/JY68) causes a promotion in the dipole moment of the sensitizer, while dye JY69 with DTP as a neighboring donor inversely results in a decrease. Besides the open-circuit voltage (VOC) and short-circuit current density (JSC) rising together with dipole moment, the power conversion efficiency (PCE) displays near linear positive correlation to the vertical dipole moment (μnormal) in this series. Finally, dye JY67 containing TPA and carbazole donor achieves the best photovoltaic performance. Accordingly, decorating such an X-shaped bridge with hetero-donors would be a promising strategy to improve the performance of multi-branched dyes in DSSCs. [ABSTRACT FROM AUTHOR]

Herein, we present the direct aqueous synthesis of manganese (Mn) doped CuInSe2 (Mn-CISe) quantum dots (QDs) under microwave irradiation to improve the photochemical properties of solar cells. As a result of Mn doping, the narrower bandgap energy of Mn-CISe leads to higher visible light absorption. The Mn-CISe QDs are therefore used as photosensitizers in quantum dot sensitized solar cells (QDSSCs), exhibiting enhanced performance which is dependent on Mn concentration. To the best of our knowledge, this is the first time to construct an Mn-CISe sensitized-TiO2 photoanode to boost the photovoltaic performance of QDSSCs. The incorporation of Mn into CISe increases short-circuit current, which is ascribed to the effective injection of the excited electrons from QDs into TiO2 and the consequent higher electron lifetime, likely through a newly formed Mn midgap in the CISe band structure. Compared to the undoped QDs, Mn-CISe QDSSCs show a shorter electron transport time (τt) and a longer electron recombination time (τr) which are studied by intensity-modulated photocurrent spectroscopy and intensity-modulated photovoltage spectroscopy, respectively. In fact, a combination of higher light-harvesting efficiency, slower charge recombination, and a longer electron lifetime gives rise to a maximum photovoltaic performance of 6.28%. [ABSTRACT FROM AUTHOR]

A novel near-infrared-light-absorbing fused-ring electron acceptor, STIC, was developed for organic solar cells. STIC exhibited a narrow bandgap with an absorption edge reaching 940 nm, which was ascribed to the strong electron-rich selenophene-thieno[3,2-b]thiophene–selenophene (ST) unit and strong intramolecular charge transfer of STIC. Also, STIC-based devices showed low open-circuit voltage (Voc) loss values, attributed to the rigid ST core providing low reorganization energy. The device based on the PBDB-T:STIC blend exhibited a power conversion efficiency (PCE) of 9.68% with a high short-circuit current density (Jsc) of 19.96 mA cm−2 and a low Voc loss of 0.55 eV. [ABSTRACT FROM AUTHOR]

Pure carbon nanotubes (CNTs) and their derivatives grafted with the regiorandom poly(3-dodecyl thiophene) (CNT-g-PDDT) and regioregular poly(3-hexylthiophene) (CNT-g-P3HT) polymers were employed to improve the morphological, optical, and photovoltaic properties of CH3NH3PbI3 perovskite solar cells. Although the grafted CNT components improved the cell characteristics, bare CNTs destroyed them. The regioregularity and graft length influences were investigated on the system behavior. The CNT nanostructures grafted with the shorter P3HT backbones demonstrated the best results, i.e., 79.9 Ω, 23.60 mA cm−2, 76%, 0.97 V and 17.40%. This originated from the higher crystalline peak intensities for both P3HT (5.6–5.8°) and CH3NH3PbI3 (14.81, 20.91, 24.11, 29.21 and 32.51°) precursors and also the larger grain sizes (5 (600 nm) versus 50 (490 nm) kDa). The perovskite + CNT-g-P3HT devices, in particular the CNTs with shorter grafts, possessed faster electron transport and lower carrier recombination compared with the other solar cells, as evidenced by the larger short-circuit current density. [ABSTRACT FROM AUTHOR]

A novel non-fullerene acceptor–donor–acceptor (A–D–A) structured small molecule acceptor material with fused ring N-alkyl dithieno[3,2-b:2′,3′-d]pyrrole (DTP) as the central donor unit and ((2-(5,6-difluoro-)3-oxo-2,3-dihydro-1H-inden-1-ylidene)malononitrile) (EG-2F) as the terminal acceptor units, named DTP-C17-4F, was designed and synthesized. DTP-C17-4F demonstrates strong near-infrared absorption, suitable energy levels, a good film morphology and high electron mobility, resulting in an outstanding short-circuit current density of 21.17 mA cm−2 without additives for organic photovoltaics. [ABSTRACT FROM AUTHOR]

In this study Ga-doped cadmium sulfide (CdS) nanowires (NWs) were grown through chemical vapor deposition. The carrier conductivities of the CdS NWs improved after the incorporation of Ga; moreover, the conductivities of the CdS NWs increased upon increasing the amount of the Ga source. Using a cation exchange method, these CdS NWs served as the source material for the preparation of Cu2S–CdS p–n heterostructured NWs. The short-circuit current, open-circuit voltage, fill factor, and power conversion efficiency of the best-performing Cu2S–CdS NW photovoltaic device were 0.152 nA, 0.245 V, 44.5%, and 0.405%, respectively, when illuminated under AM 1.5 solar light. This study demonstrates the possibility of modulating not only the properties of CdS NWs through the incorporation of dopant Ga atoms but also the photovoltaic properties of Cu2S–CdS p–n heterostructured NW devices, paving the way for the exploitation of nanostructures within optoelectronics. [ABSTRACT FROM AUTHOR]

We present here a symmetrically structured bifacial solar cell tailored by two fluorescent photoanodes and a platinum/titanium/platinum counter electrode, yielding extra-high short-circuit current densities as high as 28.59 mA cm−2 and 119.9 μA cm−2 in simulated sunlight irradiation (100 mW cm−2, AM1.5) and dark–light conditions, respectively. [ABSTRACT FROM AUTHOR]

Seven dyes 1–7 with different electron-withdrawing groups were designed and investigated based on C275, which has been the most efficient metal-free donor/acceptor dye until now to screen outstanding dyes for an organic dye-sensitized solar cell (DSSC). Some basic parameters, such as geometries, electronic structures, absorption spectra and charge recombination, were investigated by DFT and TDDFT methods, and the theoretical maximum short-circuit current density (Jmaxsc) and the electron injection lifetime (τ) were also calculated to estimate the light-harvesting abilities and electron injection efficiencies of these dyes, respectively, which adds some quantitative information for our study. Moreover, the charge recombination process was also discussed according to the distance (r) between the semiconductor surface and cation holes in the dye. The results show that all the dyes in our work exhibit ultrafast and effective electron injection with τ values in fs. Dyes 3, 5 and 7 have better light-harvesting abilities and dyes 1, 4 and 7 have better electron-collecting abilities with slower charge recombination than C275. Thus, the designed dye 7 might have superior performance in comparison with C275 and could be the most promising candidate as an organic dye in DSSCs. [ABSTRACT FROM AUTHOR]

An asymmetrical squaraine dye (Py-3) with its two electron-donating aryl groups directly linked to the electron-withdrawing squaric acid core possesses an ideal bandgap of 1.33 eV, together with an intense and broad absorption band in the range 550–950 nm. Hence, the resulting solution-processed solar cells display an impressive Jsc of 12.03 mA cm−2 and a PCE of 4.35%. [ABSTRACT FROM AUTHOR]

An asymmetrical squaraine dye (Py-3) with its two electron-donating aryl groups directly linked to the electron-withdrawing squaric acid core possesses an ideal bandgap of 1.33 eV, together with an intense and broad absorption band in the range 550–950 nm. Hence, the resulting solution-processed solar cells display an impressive Jsc of 12.03 mA cm−2 and a PCE of 4.35%. [ABSTRACT FROM AUTHOR]