Properties Of Organic Solar Cells Research Articles

Effects of functionalization of Y6 end-groups with electron-withdrawing groups on the photovoltaic properties at the donor-acceptor interfaces of PM6/Y6 OSCs: A theoretical insight

Since the high performance non-fullerene acceptor Y6 appears, many organic solar cells (OSCs) based on it and its derivatives have been fabricated and studied. These OSCs show delicate changes of open circuit voltage (V OC ), short circuit density (J SC ), and fill factor (FF) with respect to prototype PM6/Y6 OSC. So far, the effects of functionalization of Y6 end-groups with electron-withdrawing groups on the photovoltaic properties at the donor-acceptor interfaces of PM6/Y6 OSC are still not well understood. In the present work, by modelling four OSCs based on symmetrical (Y6, Y6-4Cl, and Y6-4CN) and asymmetrical (Y6-2Cl) molecules, we find that for symmetrical Y6 and Y6-4Cl based OSCs, the computed V OC s and FFs obtained with reliable computational method show the same trend as experimental data, but the computational method used does not apply for asymmetrical Y6-2Cl based OSC. In addition, with respect to fluorination, chlorination generally would bring stronger simulated interfacial absorption spectrum, the smaller exciton binding energy of local excited state of monomers and charge transfer state at the interface, smaller singlet−triplet energy gap, the higher total oscillator strength of all CT states, and larger interfacial electrostatic potential difference. In contrast, PM6/Y6-4CN has relative much lower total oscillator strength of all CT states and predicted V OC and FF than prototype Y6/PM6 though the end-groups with CN substitutions have much stronger electron withdrawing ability. Our results gain insights into the donor-acceptor interfacial properties of OSCs based on Y6 and its derivatives. • The computed V OC s and FFs of PM6/Y6 and PM6/Y6-4Cl OSCs show exactly the same trends as experiments. • PM6/Y6-4CN seems not qualified as a promising acceptor due to low predicted FF and V OC . • For asymmetrical Y6-2Cl based OSC, new computational modelling and method should be developed for V OC and FF.

Butterfly-shaped hole transport materials with outstanding photovoltaic properties for organic solar cells

Butterfly-shaped hole transport materials with outstanding photovoltaic properties for organic solar cells

Nanographene–Osmapentalyne Complexes as a Cathode Interlayer in Organic Solar Cells Enhance Efficiency over 18%

Interface engineering is a critical method by which to efficiently enhance the photovoltaic performance of nonfullerene solar cells (NFSC). Herein, a series of metal-nanographene-containing large transition metal involving dπ -pπ conjugated systems by way of the addition reactions of osmapentalynes and p-diethynyl-hexabenzocoronenes is reported. Conjugated extensions are engineered to optimize the π-conjugation of these metal-nanographene molecules, which serve as alcohol-soluble cathode interlayer (CIL) materials. Upon extension of the π-conjugation, the power conversion efficiency (PCE) of PM6:BTP-eC9-based NFSCs increases from 16% to over 18%, giving the highest recorded PCE. It is deduced by X-ray crystallographic analysis, interfacial contact methods, morphology characterization, and carrier dynamics that modification of hexabenzocoronenes-styryl can effectively improve the short-circuit current density (Jsc ) and fill factor of organic solar cells (OSCs), mainly due to the strong and ordered charge transfer, more matching energy level alignments, better interfacial contacts between the active layer and the electrodes, and regulated morphology. Consequently, the carrier transport is largely facilitated, and the carrier recombination is simultaneously impeded. These new CIL materials are broadly able to enhance the photovoltaic properties of OSCs in other systems, which provides a promising potential to serve as CILs for higher-quality OSCs.

Correlating the Molecular Structure of A‐DA′D‐A Type Non‐Fullerene Acceptors to Its Heat Transfer and Charge Transport Properties in Organic Solar Cells

AbstractEfficient heat transfer is beneficial to heat dissipation and the thermal durability of organic solar cell (OSCs). In this regard, heat transfer properties of organic semiconductors within OSCs should play important roles, but their thermal properties are rarely explored. Here, heat diffusion properties of Y‐series non‐fullerene acceptors processing different DA′D framework, named BZ4F‐5, BZ4F‐6, and BZ4F‐7 are probed; it is found that backbone rings extension from five‐ to six‐ and seven‐membered‐fused rings trigger longer phonon mean free path and higher thermal diffusivities (D) in their pristine solid films and bulk heterojunction blends. Particularly, the correlation between the thermal transport properties in Y‐series acceptors and their backbone geometry, molecule stacking, and thin‐film crystallinity is demonstrated. More importantly, both organic thin‐film transistors and OSCs confirm that thermal durability of organic semiconductor devices correlated with the thermal properties of their active layer. Although BZ5F‐6 and BZ4F‐7 based devices possess similar device performance at room temperature, superior heat dissipation in BZ4F‐7 molecule endows it with enhanced device lifetime. These results contribute to critical design criteria for future molecular optimization in photovoltaic and optoelectronic devices.

Ternary Blend Organic Solar Cells Incorporating Ductile Conjugated Polymers with Conjugation Break Spacers

A broad family of ductile semirandom donor–acceptor (D–A) copolymers with 8-carbon alkyl conjugation break spacer (CBS) units were incorporated into ternary blend organic solar cells in order to determine their impact on the electrical metrics of solar cell performance. The goal of this study was to elucidate potential co-optimization strategies for photovoltaic and mechanical properties in organic solar cells. The ternary blended active layers were based on two polymer donors and the acceptor [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM). In all cases, the majority polymer donor component was the previously reported fully conjugated semirandom polymer P3HTT-ehDPP-10%, comprised of 80% 3-hexylthiophene, 10% diketopyrrolopyrrole (DPP) with 2-ethylhexyl (eh) side chains, and 10% thiophene. As the second donor, three different classes of CBS polymers were used, where the spacer length was kept constant at 8 methylene units. The mechanical properties of these polymers are quite notable with moduli as low as 8.54 MPa and fracture strains as high as 432%. However, it was found that as ductility increased, hole mobility decreased. In this study, we observed that the hole mobilities of the ternary active layers generally increased upon increasing the content of the CBS polymer up to 15% of the overall donor fraction. The higher carrier mobilities likely contribute to the higher JSC observed in many of the ternary devices. The as-cast ternary solar cells made in ambient environment without any pre/post treatment gave strong performance up to 25% of CBS polymer loading. This work demonstrates that introducing highly stretchable CBS polymers with poor charge mobility does not adversely affect solar cell performance, offering insights into the development of ternary strategies for flexible/stretchable organic solar cells.

Status and Prospects of Aggregation-Induced Emission Materials in Organic Optoelectronic Devices.

Aggregation induced emission (AIE) luminogens (AIEgens) have great potential in the field of organic optoelectronic devices because of their highly efficient emission property in solid state. For example, high efficiency organic light-emitting diodes (OLEDs) based on AIEgens have been developed successfully. Some AIEgens also show good photovoltaic response properties for organic solar cells (OSCs) and organic photodetectors (OPDs), and lasing properties for optically pumping organic lasers (OLs). The review will cover the status and prospects of AIEgens in OLEDs, OLs, OSCs and OPDs. It is expected that AIEgens will become an important organic optoelectronic material system in the future.

Optimizing the Charge Carrier and Light Management of Nonfullerene Acceptors for Efficient Organic Solar Cells with Small Nonradiative Energy Losses

The photovoltaic properties and energy losses of organic solar cells (OSCs) based on nonfullerene acceptors (NFAs) are highly dependent on their molecular structures and aggregation morphologies. Charge carrier and light managements are important to optimize NFA molecules. Herein, four NFAs with different alkyl substituents and end groups, named BTP‐C11‐N2F, BTP‐C9‐N2F, BTP‐C9‐IC4F, and BTP‐C9‐N4F, are designed and synthesized by side‐chain shortening, end‐acceptor π‐extension, and fluorination. As a result, a favorable morphology is achieved in BTP‐C9‐N4F‐based OSCs by using typical high bandgap polymer PM6 as a donor, and this system obtains the highest power conversion efficiency of 17.0% with a short circuit current (Jsc) of 26.3 mA cm−2, an open circuit current (Voc) of 0.85 V, and a fill factor (FF) of 75.7%. In addition, its light (Jsc) and charge carrier (Voc × FF) managements relative to the Shockley–Queisser limit are also increased. Extending the conjugation of the end groups increased the energy levels of NFAs and enabled an Eloss of 0.50 eV with a nonradiative recombination loss of as low as 0.20 eV in BTP‐C11‐N2F‐based OSCs. This work provides an efficient strategy to optimize the molecular structures of nonfullerene acceptors and further improve the properties of OSCs.

Fullerene–non-fullerene hybrid acceptors for enhanced light absorption and electrical properties in organic solar cells

Two fullerene–non-fullerene hybrid acceptors, IDTIC-PC61BM (IP) and PC61BM-IDTIC-PC61BM (PIP), are synthesized by combining a non-fullerene acceptor, 3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-indanone))-5,5,11,11-tetrakis(4-hexylphenyl)-dithieno[2,3-d:2′,3′-d’]-s-indaceno[1,2-b:5,6-b’]dithiophene (IDTIC), and a fullerene derivative, phenyl-C61-butyric acid methyl ester (PC61BM). To evaluate the potential of these hybrid acceptors, we fabricate organic solar cells (OSCs) based on the four different acceptors (i.e. IP, PIP, IDTIC, and PC61BM) and the same polymer donor (PBDB-T). In IP and PIP, the IDTIC moiety compensates for the poor light absorption of PC61BM in the visible wavelength region, improving the short-circuit current density (JSC) of the hybrid acceptor-based OSCs (11.9 → 13.1 mA cm−2). Meanwhile, the charge transport and recombination properties of the PBDB-T:IDTIC devices improve significantly after the substitution of IDTIC with IP or PIP, leading to a significant increase in the fill factor (0.54 → 0.68) as well as JSC (11.8 → 13.1 mA cm−2) of the devices. Therefore, owing to the synergistic effect of the broad light absorption of IDTIC and efficient electron transport of PC61BM, the hybrid acceptor-based OSCs show significantly higher power conversion efficiencies of 8.81% (PBDB-T:PIP) and 8.17% (PBDB-T:IP) than the PBDB-T:PC61BM (7.62%) and PBDB-T:IDTIC (5.98%) OSCs. The results demonstrate the effectiveness of the hybrid acceptor design in overcoming the shortcomings of individual acceptors and improving their photovoltaic performance.

Excitation Wavelength‐Dependent Charge Generation Dynamics in a Nonfullerene Organic Solar Cell Interface

Unraveling the charge generation dynamics at the donor–acceptor (D−A) interfaces is crucial for improving the photovoltaic performances of nonfullerene acceptor‐based organic solar cells (OSCs). Herein, time‐dependent density functional theory (TDDFT) based nonadiabatic dynamics simulations are used to explore the ultrafast photoinduced dynamics at a nonfullerene D–A PTB7@PDI interface. Based on the results, it is found that such an interface exhibits distinct charge generation processes upon excitation with different wavelengths. The excitation at ≈591 nm mainly results in the local exciton |PTB7∗>, whereas the charge transfer exciton |PTB7+PDI−> also has minor contribution. Later on, the electron transfer from PTB7 to PDI, i.e., channel I charge generation process, occurs in 1 ps. The situations are much more complex when the excitation is conducted using ≈487 nm light. The initial populated excitons include local excitons |PDI∗>, |PTB7∗>, and charge transfer exciton |PTB7+PDI−>, after which both channel I and channel II charge generation take place ultrafast. However, in both situations, the charge generation processes occur within a few picoseconds, which is consistent with previous experimental work. Such ultrafast charge generation processes in a wide range of solar spectra are one of the reasons responsible for the excellent photovoltaic properties of such OSCs.

Observing long-range non-fullerene backbone ordering in real-space to improve the charge transport properties of organic solar cells

The long-range backbone ordering in Y6 solid film is reported, which benefits charge generation and carrier lifetime in PM6:Y6 heterojunctions and drives the photovoltaic efficiency towards 16.8%.

Crystallinity dictates the selection of fullerene or non-fullerene acceptors in a small molecule organic solar cell

The side chains of a molecule affect the molecular packing and crystallinity which are crucial factors determining the photovoltaic properties in organic solar cells (OSCs). In this work, two small molecule donors, BDT(X1) and BDT(X2), with identical backbone and slightly different side chains on the end groups have been designed and synthesized. Compared with BDT(X1) with linear alkyl chain, BDT(X2) featuring a branched alkyl chain in the terminal groups has larger steric hindrance and exhibits weaker crystallinity and less compact molecule stacking. Application of the two small molecule donors in OSCs shows that BDT(X1) is more suitable for IDIC, a non-fullerene acceptor, while BDT(X2) demonstrates higher OSC performance when blended with fullerene acceptor PC71BM. Morphology and grazing-incidence wide-angle X-ray scattering (GIWAXS) studies reveal that crystallinity plays a key role in determining the molecular packing and phase separation with fullerene/non-fullerene acceptors which in turn influence the charge transport and photovoltaic properties. Our results provide some guidance on selection of acceptors for a given donor and demonstrate the importance of fine tuning of the crystallinity in small molecule OSCs.

Hydrothermal synthesis of reduced graphene oxide‐anatase titania nanocomposites for dual application in organic solar cells

Lately, there has been increased interest in the design of graphene-based hybrid nanomaterials and their application to modify properties of organic solar cells (OSCs). Herein, we demonstrate an efficient route for the successful hydrothermal synthesis of reduced graphene oxide-anatase titania (RGOT) nanocomposites. Five nanocomposites with different titania concentrations, that is, RGOT-50, RGOT-75, RGOT-86, RGOT-90, and RGOT-92, were prepared. The nanocomposite RGOT-92 with the overall best properties was used to modify both the photoactive layer (P3HT:PCBM:RGOT) and hole transport layer (PEDOT:PSS:RGOT) of an OSC so as to assist in solar energy absorption by way of enhancing optical absorption and creating an efficient charge transport channel. The nanocomposites prepared consist of highly crystalline, spherical, and uniformly shaped TiO2 nanoparticles, with an average particle size of approximately 3.0 nm, deposited on the basal plane of reduced graphene oxide. Also, the nanocomposites show much reduced bandgap energies and low rates of electron-hole recombination. The incorporation of RGOT in the active layer effectively improved photon absorption, leading to high photoexciton generation. In addition, effective exciton dissociation was energetically favoured in the RGOT-modified hole transport layer (HTL), which concurs with the observed enhanced conductivity of the medium. Thus, the integration of RGOT in the active layer and HTL remarkably resulted in a high short-circuit current density (Jsc), low sheet resistance (Rs), and, consequently, improved photovoltaic performance. An enhanced photocurrent was noted, as high as 13 mA cm−2, from the OSCs by inlaying RGOT in the photoactive layer. An increased power conversion efficiency of up to 64% was achieved by the incorporation of RGOT in the photoactive layer. Thus, the utilized hydrothermal synthesis route provided nanocomposites with enhanced photoelectronic properties, with promising applications in nanoelectronic devices.

Performance-Enhancing Approaches for PEDOT:PSS-Si Hybrid Solar Cells.

The emerging energy crisis has focused significant worldwide attention on solar cells. Although crystalline silicon solar cells are currently widely used, their high cost limits the development of solar power generation. Consequently, hybrid solar cells are becoming increasingly important, especially organic-Si hybrid solar cells (HSCs). Organic-Si HSCs combine a mature technology and high efficiency with the low-temperature manufacturing process and tunable optoelectronic properties of organic solar cells. The organic material can be P3HT, carbon nanotubes, graphene, and PEDOT:PSS. Here we review the performance of PEDOT:PSS/Si HSCs and methods for improving their efficiency, such as PEDOT:PSS modification, optimization of the trapping effect, passivation of the silicon surface, addition of an interface layer, improvement of a back contact, and optimization of the metal top electrode. This Review should help fill the gap in this area and provide perspectives for the future development of the PEDOT:PSS/Si HSCs.

The influence of structural and charge transport properties of PEDOT:PSS layers on the photovoltaic properties of polymer solar cells

In this study, the effect of modification of poly(3,4‐ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) morphology on its optical, charge transport, and photovoltaic properties of organic solar cells based on the P3HT:PC60BM bulk heterojunction is presented. It is shown that the addition of isopropyl alcohol to the PEDOT:PSS polymer solution and annealing of spin‐coated PEDOT:PSS film leads to a change in its morphology, charge transport, and optical properties. By an impedance spectroscopy technique, the charge transport properties of PEDOT:PSS films were studied. It was established that the efficiency of carrier transport and the efficiency of the polymer solar cells depends on the structural features of PEDOT:PSS.

Designing Star-Shaped Subphthalocyanine-Based Acceptor Materials with Promising Photovoltaic Parameters for Non-fullerene Solar Cells.

Star-shaped three-dimensional (3D) twisted configured acceptors are a type of nonfullerene acceptors (NFAs) which are getting considerable attention of chemists and physicists on account of their promising photovoltaic properties and manifestly promoted the rapid progress of organic solar cells (OSCs). This report describes the peripheral substitution of the recently reported highly efficient 3D star-shaped acceptor compound, STIC, containing a 2-(3-oxo-2,3-dihydroinden-1-ylidene)malononitrile (IC) end-capped group and a subphthalocyanine (SubPc) core unit. The 3D star-shaped SubPc-based NFA compound STIC is peripherally substituted with well-known end-capped groups, and six new molecules (S1–S6) are quantum chemically designed and explored using density functional theory (DFT) and time-dependent DFT (TDDFT). Density of states (DOS) analysis, frontier molecular orbital (FMO) analysis, reorganization energies of electrons and holes, open-circuit voltage, transition density matrix (TDM) surface, photophysical characteristics, and charge-transfer analysis of selected molecules (S1–S6) are evaluated with the synthesized reference STIC. The designed molecules are found in the ambience of 2.52–2.27 eV with a reduction in energy gap of up to 0.19 eV compared to R values. The designed molecules S3–S6 showed a red shift in the absorption spectrum in the visible region and broader shift in the range of 605.21–669.38 nm (gas) and 624.34–698.77 (chloroform) than the R phase values of 596.73 nm (gas) and 616.92 nm (chloroform). The open-circuit voltages are found with the values larger than R values in S3–S6 (1.71–1.90 V) and comparable to R in the S1 and S2 molecules. Among all investigated molecules, S5 due to the combination of extended conjugation and electron-withdrawing capability of end-capped acceptor moiety A5 is proven as the best candidate owing to promising photovoltaic properties including the lowest band gap (2.27 eV), smallest λe = 0.00232 eV and λh = 0.00483 eV, highest λmax values of 669.38 nm (in gas) and 698.77 nm (in chloroform), and highest Voc = 1.90 V with respect to HOMOPTB7-Th–LUMOacceptor. Our results suggest that the selected molecules are fine acceptor materials and can be used as electron and/or hole transport materials with excellent photovoltaic properties for OSCs.

Design of novel thiazolothiazole-based conjugated polymer for efficient fullerene and non-fullerene organic solar cells

We report the synthesis of novel low bandgap conjugated polymer P1 comprising thiazolothiazole, benzothiadiazole and thiophene units and investigation its photovoltaic properties in organic solar cells with [70]PCBM ([6,6]-phenyl-C71-butyric acid methyl ester) and high-performing non-fullerene IT-4F acceptor (9-bis(2-methylene-((3-(1,1-dicyanomethylene)-6,7-difluoro)-indanone))-5,5,11,11-tetrakis(4-hexylphenyl)-dithieno[2,3-d:2’,3’-d’]-s-indaceno [1,2-b:5,6-b’]dithiophene). Polymer P1 showed promising results in both fullerene and non-fullerene organic solar cells. In particular, P1/IT-4F blends demonstrated enhanced charge carrier mobilities and suppressed trap-assisted recombination, which resulted in impressive short-circuit current densities and decent power conversion efficiency of 8.8 % in solar cells. The fullerene-based devices delivered efficiency of 8.2 % with remarkably high open-circuit voltages. The obtained results feature conjugated polymers based on thiazolothiazole as promising absorber materials for organic solar cells.

Application of Artificial Intelligence for Optimization of Organic Solar Cells Production Process

The study of organic solar cells (OSCs) has been rapidly developed in recent years. Organic solar cell technology is sought after mainly due to the ease of manufacture and their exclusive properties such as mechanical flexibility, light-weight, and transparency. These properties of OSCs are well-suited for unconventional applications with power conversion efficiencies more high than 10%. The flexibility of the used substrates and the thinness of the devices make OSCs ideal for roll-to-roll production. However the organic solar cells still have very low conversion efficiencies due to degradation and stability of the technology. In order to extract their full potential, OSCs have to be optimized. On the other hand the production chain of the organic solar cells (OSC) can take advantage of the use of artificial intelligence (AI). In fact the integration into the production workflow makes solar cells more competitive and efficient. This paper presents some applications of the AI for optimization of OSCs production processes Full Text: PDF ReferencesLo Sciuto, G., Capizzi, G., Coco, S., Shikler, R., "Geometric shape optimization of organic solar cells for efficiency enhancement by neural networks." (2017) Lecture Notes in Mechanical Engineering, pp. 789-796. CrossRef Barnea, S.N., Lo Sciuto, G., Hai, N., Shikler, R., Capizzi, G., Wozniak, M., Polap, D., "Photo-electro characterization and modeling of organic light-emitting diodes by using a radial basis neural network." (2017) Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics), 10246 LNAI, pp. 378-389. CrossRef Ye, L.; Hu, H.; Ghasemi, M.; Wang, T.; Collins, B.A.; Kim, J.H.; Jiang, K.; Carpenter, J.H.; Li, H.; Li, Z.; et al. "Quantitative relations between interaction parameter, miscibility and function in organic solar cells." Nat. Mater. 2018, 17, 253-260. CrossRef Haralick, R.M., Shanmugam, K., Dinstein, I.: Textural features for image classification. IEEE Trans. Syst. Man Cybern. SMC-3(6), 610-621 (1973) CrossRef Capizzi, G., Sciuto, G.L., Napoli, C., Tramontana, E., Wozniak, M.: Automatic classification of fruit defects based on co-occurrence matrix and neural networks. In: 2015 Federated Conference on Computer Science and Information Systems (FedCSIS), pp. 861-867, September 2015. CrossRef

Facile Method of Solvent-Flushing To Building Component Distribution within Photoactive Layers for High-Performance Organic Solar Cells.

Suitable donor and acceptor distribution in the blended photoactive layer benefits the charge transfer and exciton separation to boost the performance of organic solar cells (OSCs). Herein, we propose a universal solvent-flushing method for building component distribution in photoactive layers based on the different solubilities of the donor and acceptor in acetylacetone (Acac). The donor and acceptor concentration distribution through the photoactive layers is investigated by the time-of-flight secondary-ion mass spectroscopy, and the surface concentration changes are examined by contact angle measurements and atomic force microscopy tests. The charge-transfer properties of OSCs before and after Acac flushing are further investigated by the rectification ratio and light intensity-dependent Jsc and Voc measurements. For inverted OSCs based on PBDB-TF:IT-4F, the power conversion efficiency (PCE) enhances from 12.87 to 14.05%, and for a PBDB-TF:Y6-based device, the PCE also significantly increases from 15.40 to 16.51% because of greatly enhanced Jsc and FF, benefited from enhanced charge transport and suppressed charge recombination by solvent-flushing. Our findings suggest that solvent-flushing is a simply processed and easily controlled method to achieve vertical component distribution in photoactive layers to boost the performance of OSCs.

Fabrication and Photovoltaic Properties of Organic Solar Cell Based on Zinc Phthalocyanine

Herein, we report thin films’ characterizations and photovoltaic properties of an organic semiconductor zinc phthalocyanine (ZnPc). To study the former, a 100 nm thick film of ZnPc is thermally deposited on quartz glass by using vacuum thermal evaporator at 1.5 × 10−6 mbar. Surface features of the ZnPc film are studied by using scanning electron microscope (SEM) with in situ energy dispersive x-ray spectroscopy (EDS) analysis and atomic force microscope (AFM) which reveal uniform film growth, grain sizes and shapes with slight random distribution of the grains. Ultraviolet-visible (UV-vis) and Fourier Transform Infrared (FTIR) spectroscopies are carried out of the ZnPc thin films to measure its optical bandgap (1.55 eV and 3.08 eV) as well as to study chemical composition and bond-dynamics. To explore photovoltaic properties of ZnPc, an Ag/ZnPc/PEDOT:PSS/ITO cell is fabricated by spin coating a 20 nm thick film of hole transport layer (HTL)—poly-(3,4-ethylenedioxythiophene) poly(styrene sulfonic acid) (PEDOT:PSS)—on indium tin oxide (ITO) substrate followed by thermal evaporation of a 100 nm layer of ZnPc and 50 nm silver (Ag) electrode. Current-voltage (I-V) properties of the fabricated device are measured in dark as well as under illumination at standard testing conditions (STC), i.e., 300 K, 100 mW/cm2 and 1.5 AM global by using solar simulator. The key device parameters such as ideality factor (n), barrier height ( ϕ b ), junction/interfacial resistance (Rs) and forward current rectification of the device are measured in the dark which exhibit the formation of depletion region. The Ag/ZnPc/PEDOT:PSS/ITO device demonstrates good photovoltaic characteristics by offering 0.48 fill factor (FF) and 1.28 ± 0.05% power conversion efficiency (PCE), η.

Sequential Blade‐Coated Acceptor and Donor Enables Simultaneous Enhancement of Efficiency, Stability, and Mechanical Properties for Organic Solar Cells

AbstractAs a predominant fabrication method of organic solar cells (OSCs), casting of a bulk heterojunction (BHJ) structure presents overwhelming advantages for achieving higher power conversion efficiency (PCE). However, long‐term stability and mechanical strength are significantly crucial to realize large‐area and flexible devices. Here, controlling blend film morphology is considered as an effective way toward co‐optimizing device performance, stability, and mechanical properties. A PCE of 12.27% for a P‐i‐N‐structured OSC processed by sequential blade casting (SBC) is reported. The device not only outperforms the as‐cast BHJ devices (11.01%), but also shows impressive stability and mechanical properties. The authors corroborate such enhancements with improved vertical phase separation and purer phases toward more efficient transport and collection of charges. Moreover, adaptation of SBC strategy here will result in thermodynamically favorable nanostructures toward more stable film morphology, and thus improving the stability and mechanical properties of the devices. Such co‐optimization of OSCs will pave ways toward realizing the highly efficient, large‐area, flexible devices for future endeavors.