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Phenazine‐based small molecular acceptors (SMAs), which benefit from the reduced energy loss (Eloss), have emerged as promising candidates for achieving high‐efficiency organic solar cells (OSCs). Nevertheless, the potential advancements of phenazine‐based photovoltaic devices are hindered by the constrained short‐circuit current (Jsc). Though the incorporation of selenium (Se) atoms has been proven effective in enhancing Jsc, it simultaneously introduces molecular disorder stacking and charge recombination. Based on the desire to harness the full potential of phenazine structure and the benefits of Se substitution, a series of Se‐substituted phenazine‐based SMAs, namely PzIC‐SSe‐4F and PzIC‐SeSe‐4F are meticulously synthesized. Due to the increased photon harvesting capabilities, the photovoltaic device using PzIC‐SeSe‐4F demonstrated a significantly increased Jsc of 27.73 mA cm−2. Remarkably, the PzIC‐SeSe‐4F‐based device displayed an astonishing open circuit voltage (Voc) of 0.873 V, representing the highest Voc recorded among all reported symmetric Se‐substituted Y‐series SMAs‐based photovoltaic devices. Thanks to the synergistic effect of phenazine central cores and Se substitution, the PM6:PzIC‐SeSe‐4F‐based device achieves a power conversion efficiency (PCE) of 17.69%. The findings serve as a pivotal reference for further development of high‐efficiency Se‐substituted photovoltaic devices. [ABSTRACT FROM AUTHOR]

The sustainable production of energy is a field of interest to which a new requirement is now imposed: the need to be respectful of the environment. New materials and techniques are being developed, but environmental concerns impose the necessity of keeping research active towards the development of green energy. For this reason, we present the study of short polythiophene (PTh) chains (three and five monomers) and their interaction with nickel oxide, looking for properties related to solar photon harvesting in order to produce electricity. The models of the molecules were developed, and the calculations were performed with an M11-L meta-GGA functional, specially developed for electronic structure calculations. The theoretical explorations demonstrated that the geometry of the PTh molecules suffer little distortion when interacting with the NiO molecule. The calculated value of Eg lies between 2.500 and 0.412 eV for a three-ring PTh chain and between 1.944 and 0.556 eV for a five-ring PTh chain. The chemical parameters indicated that, depending on the geometry of the system, the chemical potential varies from 81.27 to 102.38 kcal/mol and the highest amount of electronic charge varies from −2.94 to 21.56 a.u. for three-monomer systems. For five-monomer systems, the values lie within similar ranges as those of the three-monomer systems. The Partial Density of States (PDOS) showed that the valence and conduction electronic bands were composed of states in the NiO and PTh rings, except for a system where there was a non-bonding interaction. [ABSTRACT FROM AUTHOR]

Ternary polymer solar cells (PSCs) consist of two structurally similar fullerene‐free small molecules as acceptors (Y11 and Y5), and D18‐Cl as polymer, which have better photovoltaic performance relative to D18‐Cl:Y11 binary PSC. The enhanced photovoltaic performance of the binary PSCs is mainly attributed to the significantly enhanced short circuit current density (JSC) and slightly enhanced fill factor. The enhanced JSC value is due to the 45 nm blueshift of the absorption peak of Y5 relative to Y11, which facilitates more efficient absorption of photons in the visible light‐wavelength band. Another reason for the enhanced JSC is the efficient charge transport and reduced exciton coupling. Meanwhile, the Y5 film has higher crystallinity and smaller lamellar spacing and π–π stacking distance relative to the Y11 film, and 35% of Y5 instead of Y11 is beneficial to improve the surface morphology, phase separation size, and crystallinity of the ternary photoactive layer. Therefore, the best ternary PSC shows higher open‐circuit voltage values relative to the D18‐Cl:Y6 binary reference PSC and higher JSC values relative to the D18‐Cl:Y11 binary PSC. Thus, blend fullerene‐free small molecules with similar molecular structures and different optical and electronic properties as acceptor materials are new insights for the development of ternary PSCs. [ABSTRACT FROM AUTHOR]

Organic ternary solar cells as a more simple, more powerful, more stability photovoltaic technology has been attracting more and more attention, and recently the power conversion efficiency has exceeded 18%. In order to promote the commercialization of organic photovoltaics, work mechanisms and the improvement origin should be researched more deeply. In addition, eco-compatible solvents and large-scale fabricating methods should be adopted along with the improvement of efficiency and stability. [Display omitted] • The mechanisms of organic ternary solar cells are discussed. • Various roles of the third component in the active layer are discussed. • The challenges and perspective of organic ternary solar cells are discussed. The record of power conversion efficiency (PCE) of organic solar cells (OSCs) is updating every day, and the value has exceeded 19% already, but it still lags behind those of commercialized inorganic solar cells. The addition of a third component not only can reduce energy loss for achieving a higher open circuit voltage (V OC), but also can enlarge the light harvesting range as well as optimize morphology for getting a higher short circuit current (J SC) and fill factor (FF). For further promoting the development of organic photovoltaic technology, this article first presents general principles of organic ternary solar cells (OTSCs), and then summarizes the recent developments of OTSCs in terms of the roles of third component. In the end, the challenges and perspectives for OTSCs are discussed. This review may provide guidance for preparing highly efficient organic ternary solar cells. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) materials like transition metal dichalcogenides and Xenes are expected to bring exciting advancements in many fields of nanotechnology. The wealth of their electronic properties makes them appealing for a broad range of applications. In particular, in the framework of optics and photonics, three emerging routes where the key role of 2D materials will push forward the current state-of-the-art will be here outlined and discussed. Exerting control over the light-driven generation of spin-polarized dissipationless currents, enhancing the photon harvesting, and engineering the light-matter interaction are three challenges for 2D materials-based optics and photonics.

To harness solar energy comprehensively, developing photocatalysts with a broad spectrum response has received enormous attention. Herein, a full‐spectrum‐responsive Bi/BiOBr:Yb3+,Er3+ (BYE/Bi) heterostructure with oxygen vacancies (OVs) is designed and fabricated using the solvothermal method with subsequent heat treatment. The surface plasmon resonance (SPR) effect of Bi metal and OVs can not only extend the light absorption spectra but also promote the charge separation efficiency. The result of upconversion (UC) luminescence shows that the SPR absorption band of Bi nanoparticles overlaps with the excitation and emission bands of BiOBr:Yb3+,Er3+ nanosheets, which can induce a near‐infrared (NIR) plasmonic energy UC process and results in an enhanced green UC luminescence. The photocatalytic BPA degradation test shows that BYE/Bi‐2 shows the best photocatalytic activity, which is about 2.13‐fold, 1.41‐fold, and 2.73‐fold higher than that of BYE under UV−visible (vis)−near infrared (NIR), vis, and NIR light irradiations, respectively. Results reveal that the enhanced photocatalytic activity is ascribed to the Bi SPR effect and UC luminescence of BiOBr:Yb3+,Er3+ nanosheets, as well as the synergistic effects of OVs. This work not only provides ideas for the development of nonmetallic plasmon‐modified UC luminescent materials but also offers a pathway to develop high‐performance full‐spectrum photocatalysts for environmental applications. [ABSTRACT FROM AUTHOR]

A series of ternary organic photovoltaics (OPVs) are fabricated with one wide bandgap polymer D18-Cl as donor, and well compatible Y6 and Y6-1O as acceptor. The open-circuit-voltage (VOC) of ternary OPVs is monotonously increased along with the incorporation of Y6-1O, indicating that the alloy state should be formed between Y6 and Y6-1O due to their excellent compatibility. The energy loss can be minimized by incorporating Y6-1O, leading to the VOC improvement of ternary OPVs. By finely adjusting the Y6-1O content, a power conversion efficiency of 17.91% is achieved in the optimal ternary OPVs with 30 wt% Y6-1O in acceptors, resulting from synchronously improved short-circuit-current density (JSC) of 25.87 mA cm−2, fill factor (FF) of 76.92% and VOC of 0.900 V in comparison with those of D18-Cl : Y6 binary OPVs. The JSC and FF improvement of ternary OPVs should be ascribed to comprehensively optimal photon harvesting, exciton dissociation and charge transport in ternary active layers. The more efficient charge separation and transport process in ternary active layers can be confirmed by the magneto-photocurrent and impedance spectroscopy experimental results, respectively. This work provides new insight into constructing highly efficient ternary OPVs with well compatible Y6 and its derivative as acceptor. [ABSTRACT FROM AUTHOR]

A power conversion efficiency (PCE) of 16.2% is achieved in PM6:BTP‐4F‐12 based organic photovoltaics (OPVs). On the basis of efficient binary OPVs, a series of ternary OPVs are constructed by incorporating MeIC as the third component. The open circuit voltages (VOCs) of ternary OPVs can be gradually increased along with the incorporation of MeIC, suggesting the formation of an alloy state between BTP‐4F‐12 and MeIC with good compatibility. The energy loss (Eloss) of ternary OPVs can be decreased compared with that of two binary OPVs, contributing to the VOC improvement of ternary OPVs. The short circuit current density (JSC) and fill factor (FF) of ternary OPVs can also be simultaneously enhanced with MeIC content up to 10 wt% in acceptors, leading to 17.4% PCE of the optimized ternary OPVs. The JSC and FF improvement of ternary OPVs is thought to result from the optimized ternary active layers with more efficient photon harvesting, exciton dissociation and charge transport. The 17.4% PCE and 79.2% FF is among the top values of ternary OPVs. This work indicates that a ternary strategy is an emerging method to simultaneously minimize Eloss and optimize photon harvesting as well as improve the morphology of active layers for realizing performance improvement for OPVs. [ABSTRACT FROM AUTHOR]

A novel small-molecule (SM) acceptor DTF-IC is designed and synthesized in this work. The power conversion efficiency (PCE) of ternary OSCs increased up to 12.14% from 10.90% by incorporating 10 wt% of DTF-IC as second acceptors into the binary OSCs consisting of PBDB-T as donor and IT-M as acceptor. This was mainly due to the large increase in short-circuit current (J sc) from 16.18 to 17.95 mA/cm2, without any drop in the open-circuit voltage (V oc) and fill factor (FF). The addition of DTF-IC enabled the donor and acceptor to form a distinct complementary absorption profile in the visible-light region, which boosted the photon harvesting in the range of 730–800 nm and consequently increased the J sc of the ternary system by 11%. Moreover, there was an energy transfer between the two SM acceptors, favorable for enhancing charge separation and transfer as well as reducing charge recombination at PBDB-T:IT-M and PBDB-T:DTF-IC interface. Simultaneously, HOMO and LUMO energy levels of DTF-IC were lower than those of PBDB-T, but still higher than those of IT-M. Thus, DTF-IC is able to provide a cascading energy level with the host donor and acceptor which are beneficial for efficient charge transfer between the acceptors and facilitating exciton dissociation and carrier transport. Meanwhile, the highly crystalline DTF-IC as a third component can improve the crystallization process of the active layer while maintaining proper phase separation. This work proposes a novel idea for non-fullerene acceptors achieved via twin spiro-type structure modifying by indanone and provides a new direction for the selection of ternary solar cell materials. [ABSTRACT FROM AUTHOR]

Abstract: Nonfullerene polymer solar cells (PSCs) are fabricated by using one wide bandgap donor PBDB‐T and one ultranarrow bandgap acceptor IEICO‐4F as the active layers. One medium bandgap donor PTB7‐Th is selected as the third component due to the similar highest occupied molecular orbital level compared to that of PBDB‐T and their complementary absorption spectra. The champion power conversion efficiency (PCE) of PSCs is increased from 10.25% to 11.62% via incorporating 20 wt% PTB7‐Th in donors, with enhanced short‐circuit current (JSC) of 24.14 mA cm−2 and fill factor (FF) of 65.03%. The 11.62% PCE should be the highest value for ternary nonfullerene PSCs. The main contribution of PTB7‐Th can be summarized as the improved photon harvesting and enhanced exciton utilization of PBDB‐T due to the efficient energy transfer from PBDB‐T to PTB7‐Th. Meanwhile, PTB7‐Th can also act as a regulator to adjust PBDB‐T molecular arrangement for optimizing charge transport, resulting in the enhanced FF of ternary PSCs. This experimental result may provide new insight for developing high‐performance ternary nonfullerene PSCs by selecting two well‐compatible donors with different bandgap and one ultranarrow bandgap acceptor. [ABSTRACT FROM AUTHOR]

Nowadays, non-fullerene electron transport material for the fabrication of organic photovoltaic devices has become one of extensive issue of research. But unfortunately, it has been observed that the replacements of the fullerene acceptors with non-fullerene acceptor materials typically led down the device efficiency. In this article, improvement in photovoltaic response of bilayer solar cells based on small molecular Zinc Phthalocyanine (ZnPc) and non-fullerene acceptor material (Perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA)) is reported via their geometrical rearrangement. The structural and optical property of ZnPc and PTCDA thin films were investigated using SEM, AFM, XRD and UV–vis absorption spectroscopy and their role on device performance is discussed in detail. It has been observed that the photovoltaic performance of the devices in PTCDA/ZnPc layer sequence exhibits 8 times higher value ofJSCwith almost doubleVOCthat collectively shows 15 times higher value of the device efficiency as compared to the devices with ZnPc/PTCDA layer sequence. The results show that ZnPc and PTCDA exhibit complimentary absorption spectra but it would be efficient only if the materials are deposited in right sequence. [ABSTRACT FROM PUBLISHER]

We present a self-organizedmethod based on defocused ion beamsputtering for nanostructuring glass substrates which feature antireflective and light trapping effects. By irradiating the substrate, capped with a thin gold (Au) film, a self-organized Au nanowire stencil mask is firstly created. The morphology of the mask is then transferred to the glass surface by further irradiating the substrate, finally producing high aspect ratio, uniaxial ripple-like nanostructures whose morphological parameters can be tailored by varying the ion fluence. The effect of a Ti adhesion layer, interposed between glass and Au with the role of inhibiting nanowire dewetting, has also been investigated in order to achieve an improved morphological tunability of the templates. Morphological and optical characterization have been carried out, revealing remarkable light trapping performance for the largest ion fluences. The photon harvesting capability of the nanostructured glass has been tested for different preparation conditions by fabricating thin film amorphous Si solar cells. The comparison of devices grown on textured and flat substrates reveals a relative increase of the short circuit current up to 25%. However, a detrimental impact on the electrical performance is observed with the rougher morphologies endowed with steep v-shaped grooves. We finally demonstrate that post-growth ion beam restructuring of the glass template represents a viable approach toward improved electrical performance. [ABSTRACT FROM AUTHOR]

We present a self-organized method based on defocused ion beam sputtering for nanostructuring glass substrates which feature antireflective and light trapping effects. By irradiating the substrate, capped with a thin gold (Au) film, a self-organized Au nanowire stencil mask is firstly created. The morphology of the mask is then transferred to the glass surface by further irradiating the substrate, finally producing high aspect ratio, uniaxial ripple-like nanostructures whose morphological parameters can be tailored by varying the ion fluence. The effect of a Ti adhesion layer, interposed between glass and Au with the role of inhibiting nanowire dewetting, has also been investigated in order to achieve an improved morphological tunability of the templates. Morphological and optical characterization have been carried out, revealing remarkable light trapping performance for the largest ion fluences. The photon harvesting capability of the nanostructured glass has been tested for different preparation conditions by fabricating thin film amorphous Si solar cells. The comparison of devices grown on textured and flat substrates reveals a relative increase of the short circuit current up to 25%. However, a detrimental impact on the electrical performance is observed with the rougher morphologies endowed with steep v-shaped grooves. We finally demonstrate that post-growth ion beam restructuring of the glass template represents a viable approach toward improved electrical performance.

An optimal PCE of 17.81% is achieved in LbL type OPVs by employing solvent additives for the layered optimization, which should be among the top level for all the LbL type binary OPVs. The performance improvement should be benefited from simultaneously improved J SC and FF due to the individually optimized photon harvesting and molecular arrangement, as well as suppressed charge recombination. [Display omitted] • A PCE of 17.81% is achieved in the optimal LBL type OPVs. • The additives can act as photon harvesting reinforcer and morphology regulator. • The increased crystallize with additive can facilitate more swell matrix for exciton diffusion. In this work, layer-by-layer (LbL) type OPVs are constructed with wide bandgap polymer PNTB6-Cl as donor and nonfullerene material BTP-4F-12 as acceptor. The layered optimization strategy is employed via separately incorporating the diphenyl ether (DPE) and 1,8-diiodooctane (DIO) into PNTB6-Cl chlorobenzene solution and BTP-4F-12 chloroform solution. A power conversion efficiency (PCE) of 17.81% was achieved from the optimal LbL type OPVs with two solvent additives, which should be among the top level for LBL type binary OPVs. The incorporation of DPE and DIO can separately induce more ordered PNTB6-Cl and BTP-4F-12 orientation, which should contribute to charge transport with suppressed charge recombination in active layers. Meanwhile, BTP-4F-12 crystallization is strongly increased with the incorporation of DIO, which should facilitate more swell matrix for exciton diffusion in active layers. Over 13% PCE improvement can be realized in LbL type OPVs by incorporating two additives, benefiting from simultaneously improved short circuit current density (J SC) of 26.89 mA cm−2 and fill factor (FF) of 75.79%. Meanwhile, the PCE of optimized LbL type OPVs is higher than that of 17.33% for the optimized OPVs with bulk-heterojunction (BHJ) configuration, which reveals that layered optimization strategy should be a promising approach to achieve highly efficient LbL type OPVs. [ABSTRACT FROM AUTHOR]

Superior photon absorption in ordered nanowire arrays has been demonstrated recently. However, systematic studies are still missing to explore the limits of their implementation as functional photonic devices. With emphasis on silicon nanowires, we investigated the effects of nanowire diameter, length, morphology, and pitch on the photon absorption within the visible solar spectrum based on simulations. Our results reveal that these parameters are crucial but disclose a path to improve the absorbance drastically. PACS: 78.40.Fy; 78.67.Uh; 78.67.-n [ABSTRACT FROM AUTHOR]

Propagating optical eigenmodes are found in densely packed monolayers of plasmonic nanoparticles on a metal mirror. FDTD numerical calculations show that these 2D waves carry strongly confined and amplified light energy directly in the layer of nanoparticles or in the gap between the nanoparticles and the mirror. The extreme amplification of light intensity and localization at the nanoscale offer a high potential of these waves for photon emission, light harvesting, and waveguiding applications. [ABSTRACT FROM AUTHOR]

Abstract: Herein we present a methodology for improving the power conversion efficiency of organic solar cells made by photoactive layers of poly(3-hexylthiophene) (P3HT) and phenyl-C61 butyric acid methyl ester (PCBM) of non-optimized microstructure. In our study we achieve a 47% improvement in the power conversion efficiency (PCE) of the device by utilizing a thiophene-based quinoid (QBT) moiety as the third component in the P3HT:PCBM:QBT photoactive layers. Based on a set of independent characterization experiments we address the QBT composition dependent photophysical, electrical, thermal, structural and morphology-related properties of the ternary photovoltaic P3HT:PCBM:QBT system for elucidating the origin of the PCE improvement. In small amounts (0.3–0.6wt%), QBT serves as a nucleation agent, it enlarges the size of the P3HT crystallites by 15% and it increases the fraction of well-ordered P3HT chains in the P3HT:PCBM:QBT layer. The improved microstructure of the photoactive layer in combination with the QBT-assisted photo-induced hole transfer step from PCBM to P3HT, lead to an increase of the charge photogeneration yield in the P3HT:PCBM:QBT triple bulk heterojunction. The relatively small optical gap of QBT facilitates a resonant energy transfer step from the photoexcited PCBM to the QBT followed by a charge transfer process between QBT and the P3HT matrix. Based on these findings we propose general guidelines for the design of next generation functional additives to be used in organic photovoltaics. [Copyright &y& Elsevier]

Abstract: Two series of P3HT-based polymer solar cell (PSCs) only with different electron acceptors PC70BM or PC60BM were investigated under the same conditions. The PSCs with PC70BM as the electron acceptor exhibit a relatively strong and broad absorption in the visible range and high external quantum efficiency, which results in a relatively high open circuit voltage (V oc ) of 0.62V, short circuit current density (J sc ) of 11.85mA/cm2 and power conversion efficiency (PCE) of 3.52%. The PSCs with PC60BM as the electron acceptor have a relatively low V oc of 0.58V, J sc of 10.68mA/cm2 and PCE of 3.02% due to the weak absorption of PC60BM in the visible light range. The function of PC70BM instead of PC60BM as electron acceptor could be summarized as follows: i) the strong absorption PC70BM in the visible range results in much more photon harvesting; ii) the relatively low electron mobility and relatively big size of PC70BM molecule influences the charge transporting and phase separation. The ultimate performances of PSCs are codetermined by the photon harvesting, exciton dissociation, charge carrier transport and collection. [Copyright &y& Elsevier]

Abstract: Organic semiconductors usually show high absorption coefficients only over a limited spectral range. This has to be taken into account when designing organic solar cells with low-energy gap absorbers, as it is likely that these cells will have reduced harvesting abilities for photons of higher energy. We will present two routes to tackle this problem via luminescence and energy transfer and outline three novel concepts of how to integrate these mechanisms. We use an efficient low-energy gap organic solar cell based on zinc-phthalocyanine and fullerene C60 as a model system. [Copyright &y& Elsevier]

Ternary strategy has been confirmed as an efficient method to improve the power conversion efficiency (PCE) of organic photovoltaics (OPVs). The 15.7% PCE is achieved from PM6:Y6 based binary OPVs. One nonfullerene acceptor Br-ITIC and fullerene derivative PC 71 BM are selected as the third component on the basis of efficient binary OPVs, respectively. The optimized ternary OPVs exhibit 16.4% and 16.2% PCE with Br-ITIC and PC 71 BM as the third component, respectively, corresponding to the short circuit current density (J SC) of 25.5 mA cm−2 vs. 25.6 mA cm−2, open circuit voltage (V OC) of 0.854 V vs. 0.836 V and fill factor (FF) of 75.1% vs. 75.6%. The advantage on photovoltaic parameters of two ternary OPVs may be recombined into one cell by employing PC 71 BM as the fourth component. A 16.8% PCE is achieved from the optimized quaternary OPVs, resulting from the further increased J SC of 25.8 mA cm−2 and FF of 76.4% compared with the optimized ternary OPVs. The third party certificated PCE of quaternary OPVs is 16.2%. In comparison to 15.7% PCE of the binary OPVs, about 4.5% and 7.0% PCE improvement are step-by-step achieved from the optimized ternary and quaternary OPVs, respectively. Multi-components strategy may provide enough room to achieve highly efficient OPVs. Based on highly efficient binary OPVs, Br-ITIC and PC 71 BM were successively incorporated into the active layer as the third and the fourth component, leading to the step-by-step PCE improvement from 15.7% to 16.4% and then to 16.8%. Image 1 • A PCE of 16.8% is achieved in the optimized quaternary OPVs. • Photogenerated exciton distribution can be optimized by employing multi-components strategy. • PC 71 BM can act as a morphology regulator to optimize molecular arrangement and phase separation. [ABSTRACT FROM AUTHOR]