Ternary Active Layers Research Articles

Largely improved bulk-heterojunction morphology in organic solar cells based on a conjugated terpolymer donor via a ternary strategy

In this wok, a D1-A-D2-A random terpolymer donor PFBT4T-BDT10 was synthesized for application in organic solar cells (OSCs). With fullerene derivative PC71BM as the acceptor, the PFBT4T-BDT10:PC71BM binary active layer delivered a very low short-circuit current (Jsc) of 5.87 mA cm−2 and a low fill factor (FF) of 53.8%, leading to a poor efficiency of 2.40%. With a small fused ring electron acceptor IDIC as the third component, the PFBT4T-BDT10:IDIC:PC71BM ternary active layers displayed a largely elevated efficiency up to 10.17%, corresponding to significantly elevated Jsc of 21.12 mA cm−2 and FF of 63.9%. The favorable morphology and the broader absorption are the main reasons for the elevation of Jsc. It was found that IDIC could act as a morphology regulator in the ternary blends, not only restricting the aggregation of PC71BM but also maintaining the crystallization of PFBT4T-BDT10. Our work highlights the importance of ternary blend strategy for random terpolymers.

Nontoxic pyrite iron sulfide nanocrystals as second electron acceptor in PTB7:PC71BM-based organic photovoltaic cells.

Herein, we report the synthesis of nontoxic pyrite iron sulfide (FeS2) nanocrystals (NCs) using a two-pot method. Moreover, we study the influence of these NCs incorporated into the PTB7:PC71BM active layer of bulk-heterojunction ternary organic photovoltaic (OPV) cells. The OPV devices are fabricated with the direct configuration glass/ITO/PEDOT:PSS/PTB7:PC71BM:FeS2/PFN/FM. The Field’s metal (FM) is a eutectic alloy composed of 32.5% Bi, 51% In and 16.5% Sn by weight that melts at 62 °C. It is deposited on the active layer/PFN under atmospheric conditions. Ternary active layers are prepared by adding small amounts of the semiconducting FeS2 NCs at different weight ratios of 0.0, 0.25, 0.5, and 1.0 wt % with respect to the electron donor PTB7. With respect to the reference device (without FeS2), a 21% increase in the power conversion efficiency (PCE) is observed for OPVs with 0.5 wt % FeS2, such that the PCE of the OPVs is enhanced from 5.69 to 6.47%. According to the Kruskal–Wallis and Mann–Whitney statistical tests, all OPV devices follow the same trend.

Ternary Polymer Solar Cells Facilitating Improved Efficiency and Stability.

The use of a ternary active layer offers a promising approach to enhance the power conversion efficiency (PCE) of polymer solar cells (PSCs) via simply incorporating a third component. Here, a ternary PSC with improved efficiency and stability facilitated by a new small molecule IBC-F is demonstrated. Even though the PBDB-T:IBC-F-based device gives an extremely low PCE of only 0.21%, a remarkable PCE of 15.06% can be realized in the ternary device based on PBDB-T:IE4F-S:IBC-F with 20% IBC-F, which is ≈10% greater than that (PCE = 13.70%) of the control binary device based on PBDB-T:IE4F-S. The improvement in the device performance of the ternary PSC is mainly attributed to the enhancement of fill factor, which is due to the improved charge dissociation and extraction, suppressed bimolecular and trap-assisted recombination, longer charge-carrier lifetime, and enhanced intermolecular interactions for preferential face-on orientation. Additionally, the ternary device with 20% IBC-F shows better thermal and photoinduced stability over the control binary device. This work provides a new angle to develop the third components for building ternary PSCs with enhanced photovoltaic performance and stability for practical applications.

Efficient Exploration of the Composition Space in Ternary Organic Solar Cells by Combining High‐Throughput Material Libraries and Hyperspectral Imaging

AbstractOrganic solar cells based on ternary active layers can lead to higher power conversion efficiencies than corresponding binaries, and improved stability. The parameter space for optimization of multicomponent systems is considerably more complex than that of binaries, due to both, a larger number of parameters (e.g., two relative compositions rather than one) and intricate morphology–property correlations. Most experimental reports to date reasonably limit themselves to a relatively narrow subset of compositions (e.g., the 1:1 donor/s:acceptor/s trajectory). This work advances a methodology that allows exploration of a large fraction of the ternary phase space employing only a few (<10) samples. Each sample is produced by a designed sequential deposition of the constituent inks, and results in compositions gradients with ≈5000 points/sample that cover about 15%–25% of the phase space. These effective ternary libraries are then colocally imaged by a combination of photovoltaic techniques (laser and white light photocurrent maps) and spectroscopic techniques (Raman, photoluminescence, absorption). The generality of the methodology is demonstrated by investigating three ternary systems, namely PBDB‐T:ITIC:PC70BM, PTB7‐Th:ITIC:PC70BM, and P3HT:O‐IDFBR:O‐IDTBR. Complex performance‐structure landscapes through the ternary diagram as well as the emergence of several performance maxima are discovered.

Over 16.7% efficiency of ternary organic photovoltaics by employing extra PC71BM as morphology regulator

Ternary organic photovoltaics (OPVs) are fabricated with PBDB-T-2Cl:Y6 (1:1.2, wt/wt) as the host system and extra PC71BM as the third component. The PBDB-T-2Cl:Y6 based binary OPVs exhibit a power conversion efficiency (PCE) of 15.49% with a short circuit current ( J SC) of 24.98 mA cm−2, an open circuit voltage ( V OC) of 0.868 V and a fill factor (FF) of 71.42%. A 16.71% PCE is obtained in the optimized ternary OPVs with PBDB-T-2Cl:Y6:PC71BM (1:1.2:0.2, wt/wt) active layer, resulting from the synchronously improved J SC of 25.44 mA cm−2, FF of 75.66% and the constant V OC of 0.868 V. The incorporated PC71BM may prefer to mix with Y6 to finely adjust phase separation, domain size and molecular arrangement in ternary active layers, which can be confirmed from the characterization on morphology, 2D grazing incidence small and wide-angle X-ray scattering, as well as Raman mapping. In addition, PC71BM may prefer to mix with Y6 to form efficient electron transport channels, which should be conducive to charge transport and collection in the optimized ternary OPVs. This work provides more insight into the underlying reasons of the third component on performance improvement of ternary OPVs, indicating ternary strategy should be an efficient method to optimize active layers for synchronously improving photon harvesting, exciton dissociation and charge transport, while keeping the simple cell fabrication technology.

Ternary small molecules organic photovoltaics exhibiting 12.84% efficiency

Small molecules organic photovoltaics (SMPVs) were prepared with DR3TSBDT as donor, narrow band gap material Y6 and broad band gap material PC71BM as acceptor. The Y6 based binary SMPVs exhibit a power conversion efficiency (PCE) of 10.53%, with short-circuit current density (JSC) of 21.67 mA cm−2, open-circuit voltage (VOC) of 0.879 V and fill factor (FF) of 55.21%. A 12.84% PCE is achieved from the optimized ternary SMPVs with 40 wt% PC71BM in acceptors, which is attributed to the enhanced JSC of 22.19 mA cm−2 and FF of 67.27% resulting from the well-optimized phase separation with PC71BM as morphology regulator. Hollow spherical structure of PC71BM with high electron mobility may connect Y6 molecules to form the more continuous electron transport channels in ternary active layers. Meanwhile, DR3TSBDT molecular arrangement can be markedly adjusted by incorporating PC71BM to form 3D texture structure. The well-optimized phase separation degree and molecular arrangement in ternary active layers can well support the enhanced FFs of ternary SMPVs compared with that of binary SMPVs. Over 21% PCE improvement is achieved by employing ternary strategy with 40 wt% PC71BM in acceptors, the 12.84% PCE should be among the highest values of SMPVs.

Two Well-Compatible Acceptors with Efficient Energy Transfer Enable Ternary Organic Photovoltaics Exhibiting a 13.36% Efficiency.

Organic photovoltaics (OPVs) are fabricated with PM6 as donor and T6Me, IT-2F, or their mixture as acceptor. A 13.36% power conversion efficiency (PCE) is achieved from the optimized ternary OPVs with 50 wt% IT-2F in acceptors, which is attributed to the enhanced photon harvesting of ternary active layers and improved exciton utilization efficiency through energy transfer from IT-2F to T6Me. The efficient energy transfer from IT-2F to T6Me can be confirmed from the photoluminescence spectra of neat and blend films, which may provide additional channels to enhance exciton utilization efficiency for achieving short-circuit current density (JSC ) improvement of ternary OPVs. It should be highlighted that the fill factor (FF) of ternary OPVs can be monotonously increased along with the incorporation of IT-2F, indicating the gradually optimized phase separation degree of ternary active layers. The third component IT-2F plays a key role in optimizing phase separation as a morphology regulator. Over 8% PCE improvement is achieved in the optimized ternary OPVs compared with the over 12% PCEs of the corresponding binary OPVs, respectively. This work indicates that the performance of ternary OPVs can be well optimized by carefully picking materials with good compatibility and complementary absorption spectra, as well as the appropriate energy levels.

Building a planar single and binary blend stack ternary organic solar cells

Higher efficiency ternary organic solar cells (OSCs) can be built by capping the photoactive layer of a binary blend OSC device with a planar single photovoltaic layer, with an absorption spectrum complementary to that for the original blend layer. A ternary active layer material system of two donors poly (3-hexylthiophene) and Poly[2,6-(4,4-bis-(2-ethylhexyl)-4H-cyclopenta [2,1-b;3,4-b′] dithiophene)-alt-4,7(2,1,3-benzothiadiazole)] and an acceptor [6,6]-Phenyl C61 butyric acid methyl ester is considered in this work. From the various possibilities of building ternary device with a binary blend layer and planar single layer stacks, the low efficiency options are eliminated. Simulation studies of the final structure are carried out to decide the optimum thicknesses of the different photovoltaic layers. The optimised ternary device fabricated shows an improvement in power conversion efficiency of up to 23.5% over the base binary blend solar cells. The primary contribution to efficiency improvement is from the increase in short circuit current from the increased harvest of photons by the planar single capping layer.

13.26% Efficiency Polymer Solar Cells by Optimizing Photogenerated Exciton Distribution and Phase Separation with the Third Component

Ternary polymer solar cells (PSCs) are designed by incorporating varied PC71BM into a PBDB‐T:INPIC‐Si‐based binary system. The PC71BM incorporation can replenish weak absorption of PBDB‐T and INPIC‐Si in the short wavelength from 300 to 500 nm. Effective charge transport channels can be formed in ternary active layers due to good compatibility of the used materials. The optimized ternary PSCs exhibit a power conversion efficiency (PCE) of 13.26% with short‐circuit current density (JSC) of 20.98 mA cm−2, open‐circuit voltage of 0.892 V, and fill factor (FF) of 70.84%. The 13.26% PCE is among the top values for ternary PSCs with fullerene derivative and nonfullerene materials as acceptors. An approximately 12.5% PCE improvement is obtained compared with INPIC‐Si‐based binary PSCs, originating from simultaneously increased JSC and FF of the optimized ternary PSCs. The balanced photon harvesting is obtained in the whole wavelength range by regulating PC71BM content in acceptors, leading to increased JSC of ternary PSCs. The molecular arrangement and phase separation are well optimized in ternary blend films, resulting in the enhanced FF of ternary PSCs. The photogenerated exciton distribution is optimized according to optical field distribution of ternary active layers, which further support the JSC and FF improvement.

Ternary Blended Fullerene‐Free Polymer Solar Cells with 16.5% Efficiency Enabled with a Higher‐LUMO‐Level Acceptor to Improve Film Morphology

AbstractTernary approaches to solar cell design utilizing a small bandgap nonfullerene acceptor as the near infrared absorber to increase the short‐circuit current density always decreases the open‐circuit voltage. Herein, a highly efficient polymer solar cell with an impressive efficiency of 16.28 ± 0.20% enabled by an effective voltage‐increased ternary blended fullerene‐free material approach is reported. In this approach, the structural similarity between the host and the higher‐LUMO‐level guest enables the two acceptors to be synergized, obtaining increased open‐circuit voltage and fill factor and a small increase of short‐circuit current density. The same beneficial effects are demonstrated by using two host binary systems. The homogeneous fine film morphologies and the π–π stacking patterns of the host blend are well maintained, while larger donor and acceptor phases and increased lamellar crystallinity, increased charge mobilities, and reduced monomolecular recombination can be achieved upon addition of the guest nonfullerene acceptor. The increased charge mobilities and reduced monomolecular recombination not only contribute to the improved fill factor but also enable the best devices to be fabricated with a relatively thicker ternary blended active layer (110 vs 100 nm). This, combined with the absorption from the added guest acceptor, contribute to the increased short‐circuit current.

Enhancing performance of ternary blend photovoltaics by tuning the side chains of two-dimensional conjugated polymer

Abstract We prepared the ternary blends active layer by incorporating a new two-dimensional donor-acceptor (D/A) conjugated polymer (BDTTBO) comprising benzo-dithiophene-thiophene-thiophene-benzo oxadiazole chemical units that has three different conjugated side chains bithiophene (BT), benzothiophene (BzT) and thienothiophene (TT) BDTTBO-BT, BDTTBO-BzT and BDTTBO-TT into poly (benzodithiophene-fluorothienothiophene) (PTB7-TH) and PC71BM as for organic photovoltaics (OPVs). We expected that incorporating these BDTTBO with different side chains into the blend of PTB7-TH and PC71BM not only can broaden the absorption of solar spectrum thereby increasing short-circuit current density but also tune the packing of PTB7-TH and the dispersion of PC71BM. In particular, we found that incorporating 10% of BDTTBO-BT to form the PTB7-TH: BDTTBO-BT: PC71BM ternary blend (active layer) device could improve the power conversion efficiency to 10.4% from 9.0% for the binary blend of PTB7-TH: PC71BM device—a relative increase of 15%. We examined the packing orientations of the PBDTTBO: PTB7-TH:PC71BM ternary blend films using synchrotron two-dimensional grazing-incidence wide-angle X-ray scattering, and found that the incorporation of 10% relatively higher crystallinity PBDTTBO-BT, PBDTTBO-BzT or PBDTTBO-TT not only altered the packing orientation of PTB7-TH substantially but also reduced PC71BM cluster size in the ternary blend system, as compared to that in the case of PTB7-TH with PC71BM binary blend, thereby providing more pathways for electrons and thus enhancing the carrier transport in the ternary blend, as evidenced by the carrier mobility.

Understanding the effect of N2200 on performance of J71: ITIC bulk heterojunction in ternary non-fullerene solar cells

Abstract None-fullerene solar cells with ternary architecture have attracted much attention because it is an effective approach for boosting the device power conversion efficiency. Here, the crystalline polymer N2200 as the third component is integrated into J71:ITIC bulk heterojunction. A series of characterizations indicate that N2200 could increase photo-harvesting, balanced hole and electron mobilities, enhanced exciton dissociation, and suppressed charge recombination, which result in the comprehensive improvement of open circuit voltage, short circuit current and fill factor in the device. Moreover, after introduction of N2200, the morphology of the ternary active layer is optimized, and the film crystallinity is improved. This work demonstrates that adding a small quantity of high crystallization acceptor into non-fullerene donor: acceptor mixture is a promising strategy toward developing high-performance organic solar cells.

Ternary polymer solar cells with alloyed donor achieving 14.13% efficiency and 78.4% fill factor

The power conversion efficiency (PCE) reaches to 12.63% or 12.19% for polymer solar cells (PSCs) based on PM6 or J71 as donor and Br-ITIC as acceptor, respectively. A series of ternary PSCs with two donors were fabricated by combining the merits of the two binary PSCs. The PM6 and J71 prefer to form alloyed donor due to the good compatibility, which is beneficial to finely optimize photon harvesting and phase separation of ternary active layers, leading to simultaneous improvement of short-circuit current density (JSC) and fill factor (FF). The improved JSC and FF can well make up for the slight loss of open-circuit voltage (VOC). The optimized ternary PSCs with 20 wt% J71 in donors achieve a PCE of 14.13% and a FF of 78.4%. More than 11% PCE improvement is achieved by adopting ternary strategy on the basis of two binary PSCs with PCE over 12%, also keeping simple fabrication technology.

Ternary Active Layers for Neutral Color Semitransparent Organic Solar Cells with PCEs over 4%

Ternary blend active layers that include an additional electron donor or electron acceptor material provide the means to easily tune the transmission properties of semitransparent organic solar cel...

Ternary polymer solar cells with alloyed non-fullerene acceptor exhibiting 12.99% efficiency and 76.03% fill factor

Ternary polymer solar cells (PSCs) were purposely designed according to the key photovoltaic parameters of PBDB-T-2F based binary PSCs with FTTCN or IT-2F as acceptor. Although power conversion efficiency (PCE) of FTTCN based binary PSCs is 10.52% and lower than 12.01% of IT-2F based binary PSCs, the relatively large open circuit voltage (VOC) of 1.01 V is achieved compared with 0.920 V of IT-2F based binary PSCs. The PCE of the optimized ternary PSCs arrives to 12.99% with 20 wt% FTTCN in acceptors, resulting from the simultaneously increased short-circuit current density (JSC) of 18.18 mA/cm2, VOC of 0.940 V and fill factor (FF) of 76.03% in comparison to IT-2F based binary PSCs. Ternary PSCs exhibit the monotonously increased VOCs and over 70% FFs along with FTTCN content increase, indicating that FTTCN and IT-2F alloyed acceptor may be formed due to their good compatibility. The morphology of ternary active layers can be well optimized by adjusting FTTCN content, and three photovoltaic parameters can be well balanced for achieving 12.99% PCE. Over 8% PCE improvement can be achieved by employing ternary strategy. This work indicates that alloyed non-fullerene acceptor should have great potential to achieve efficient ternary PSCs with simultaneously increased three photovoltaic parameters.

利用双给体实现可见光范围高探测率有机光电探测器

利用双给体实现可见光范围高探测率有机光电探测器

Review Article: Atomic layer deposition for oxide semiconductor thin film transistors: Advances in research and development

This article is a review of recent research and development advances in oxide thin film transistors (TFTs) fabricated by atomic layer deposition (ALD) processes. The ALD process is remarkable as it offers accurate control of film thickness and composition as well as the ability to achieve excellent uniformity over large areas at relatively low temperatures. Firstly, an introduction to n-type oxide TFTs is provided with a focus on the development of active-layer material combinations from binary oxide active layers, like zinc oxide and indium oxide, to ternary and quaternary oxide active layers formed by doping with elements such as gallium or tin to achieve high mobility and high device stability for TFTs. Secondly, ALD p-type channel oxide TFTs are also introduced, which are required for the realization of many types of low-power circuits, such as complementary metal oxide semiconductor devices.

Efficient Ternary Organic Solar Cells with Two Compatible Non-Fullerene Materials as One Alloyed Acceptor.

Efficient ternary organic solar cells (OSCs) are fabricated by employing a polymer PBT1-C as the donor and two non-fullerene materials, MeIC and MeIC2, as one alloyed acceptor. The optimized ternary OSCs with 30 wt% MeIC2 in acceptors achieve a power conversion efficiency (PCE) of 12.55%, which is much higher than that of 11.47% for MeIC-based binary OSCs and 11.41% for MeIC2-based binary OSCs. The >9.4% improvement in PCE is mainly attributed to the optimized photon harvesting and morphology of ternary active layers, resulting in the simultaneously improved short-circuit current and fill factor. Furthermore, good compatibility and similar lowest unoccupied molecular orbital energy levels of MeIC and MeIC2 are beneficial to form one alloyed acceptor for efficient electron transport in the ternary active layers. This work may provide new insight when selecting the third component for preparing efficient ternary OSCs.

Ternary polymer solar cells based-on two polymer donors with similar HOMO levels and an organic acceptor with absorption extending to 850 nm

Abstract Ternary blending is an effective way to realize higher short circuit current density (Jsc) and higher power conversion efficiency (PCE) of the polymer solar cells (PSCs) by broadening and enhancing light harvests. In this work, we fabricated the ternary PSCs by using a narrow bandgap n-type organic semiconductor (n-OS) BT-IC with absorption edge extending to 850 nm as acceptor and two absorption-complementary conjugated polymer J51 and PTB7-Th with similar HOMO energy levels as donor. The ternary PSCs based on J51: PTB7-Th: BT-IC (0.5:0.2:1, w/w) without additive treatment demonstrated a higher PCE of 10.32% with a Voc of 0.79 V, a higher Jsc of 19.55 mA cm−2, and a FF of 67.0%. In addition, the morphology of the ternary blend active layer of the devices is quite stable after long-term thermal annealing at 130 °C.

36% Enhanced Efficiency of Ternary Organic Solar Cells by Doping a NT-Based Polymer as an Electron-Cascade Donor.

In recent years, ternary organic photovoltaic cells (OPVs) have been dedicated to improving power conversion efficiency (PCE) by broadening optical absorption spectra. Ternary OPVs with different poly[thieno[3,2-b]thiophene-2,5-diyl-alt-4,9-bis(4-(2-decyltetradecyl)thien-2-yl)naphtho[1,2-c:5,6-c’]bis[1,2,5]thiadiazole-5,5′-diyl] (PTT-DTNT-DT) doping concentrations were designed and the effect of PTT-DTNT-DT as a complementary electron donor on the performance of OPVs was investigated. The optimized PCE of OPVs was increased from 3.42% to 4.66% by doping 20 wt % PTT-DTNT-DT. The remarkable improvement in the performance of the ternary device is mainly attributed to the sharp increase in the short-circuit current density and fill-factor. The major reasons have been systematically studied from atomic force microscopy, electrochemical impedance spectroscopy, surface energy, space charge limited current and photocurrent behavior. It has been found that the separation of excitons and the transportation of charge are enhanced while light absorption is increased, and the charge recombination also decreases due to the optimization of the cascade energy level and the morphology of the ternary active layer. The results show that it is feasible to improve the performance of ternary OPVs by their complementary absorption.