High PCE Research Articles

High-Efficiency (21.4%) Carbon Perovskite Solar Cells via Cathode Interface Engineering by using CuPc Hole-Transporting Layers.

Carbon perovskite solar cells (C-PSCs) represent a promising photovoltaic technology that addresses the long-term operating stability needed to compete with commercial Si solar cells. However, the poor interface contacts between the carbon electrode and the perovskite result in a gap between C-PSC's performances and state-of-the-art PSCs based on metallic back electrodes. In this work, Cu (II) phthalocyanine (CuPc) was rediscovered as an effective hole-transporting material (HTM) to be coupled with carbon electrodes. In particular, based on computional studies and VASP calculations, it is found that the tetragonal structure of CuPc could efficiently coordinated to perovskite layer via N and Cu atoms to Pb and I atoms, respectively. By systematically optimizing the concentration of the CuPc HTL solution, and screening the coupling of CuPc HTL with two types of carbon electrodes, based on carbon black:graphite mixture and reduced graphene oxide, respectively, a maximum power conversion efficiency of 21.4% has been achieved. In addition, our cells demonstrate satisfactory stability under thermal ageing at 85°C; 20% PCE loss after more than 200 h and shelf-life ageing 20 days with 1.3% PCE loss in ambient conditions (ISOS-D-1). These findings are interesting in developing commercially competitive C-PSCs, as they combine both high PCE and stability.

Synergistically Halogenated and Methoxylated Thiophene Additive Enables High-Performance Organic Solar Cells.

Morphology control plays a key role for improving efficiency and stability of bulk heterojunctions (BHJ) organic solar cells (OSCs). Halogenation and methoxylation are two separate ways successfully adopted in additives for morphology optimization. In this work, these two strategies are combined together. A series of halogenated methoxylated thiophenes is designed and synthesized as volatile additives to control the evolution of the BHJ morphology. Specifically, the addition of 2,5-diiodo-3,4-dimethoxythiophene (MT-I) prominently improves the performance and photostability of OSCs. Computational simulations reveal the noncovalent interactions of MT-I with the active layer materials that corresponds to the inhibition of excessive aggregation behavior of PM6 and Y6 during the film-forming process, facilitating favorable phase separation and enhanced molecular stacking. Consequently, PM6:Y6-based binary OSCs with the treatment of MT-I achieves a high PCE of 17.93%. Furthermore, MT-I demonstrates broad feasibility across diverse high-efficiency BHJ OSCs, leading to superior photovoltaic performance (PCE over 18%). This study offers valuable guidance for the design and application of high-performance additives in future endeavors.

Optimization of Several Parameters Towards 30% Efficiency Perovskite Based Solar Cell Using SCAPS-1D Software

A simulated perovskite solar cell based on a P3HT/MAPbI3/C60 structure is examined to achieve 30% PCE using SCAPS-1D software. Several aspects of the perovskite layer were evaluated, including the perovskite layer thickness, CB and VB effective density of state, band gap, and electron affinity. These factors show great influence on the device performance. The best device based on the best examined parameter has exhibited a PCE of 32.1% correlated with FF of 84.8%, VOC of 1.23V and JSC of 30.77 mA.cm-2. Such a result is promising towards achieving high PCE for perovskite-based solar cells by optimizing several factors, including active layer thickness, energy band gap, electron affinity, and effective state density for CB and VB. However, for the experimentally produced solar cells, the preparation condition and other factors may render this result. A low effective DOS of (1x1016m-3) is desired for both CB and VB to achieve high solar cell performance.

Molecular design of ternary copolymers with high photothermal performance in the near-infrared window for effective treatment of gliomas in vivo.

Photothermal therapy (PTT) is a promising approach for treating glioblastoma multiforme (GBM) with minimal invasiveness and favorable outcomes. Conjugated polymers as photothermal agents offer stability, biocompatibility, and adjustable absorption capacity. However, existing polymers face limitations in achieving high photothermal conversion efficiency and strong absorbance in the near-infrared (NIR) region, posing a risk of damaging healthy tissues surrounding GBM during precise PTT. Herein, a molecular design strategy was developed to create a series of ternary copolymers by incorporating various π-conjugated molecules into both the main chain and side chain. Through this approach, PDTT-253, with rational molar contents of three units and a relatively minor twisted architecture between donors and π-bridges, demonstrated strong NIR absorbance and high PCE of 85.1 % at 808 nm. Furthermore, PDTT-253 nanoparticles exhibited exceptional photothermal stability, photostability, and prolonged storage validity period. In vitro studies revealed high biocompatibility and strong NIR photothermal killing efficacy of PDTT-253 NPs when incubated with U87 cells. Following the injection of PDTT-253 NPs into U87 glioma-bearing mice, a single 808 nm laser irradiation treatment resulted in the inhibition of glioma growth, with the ablated glioma being entirely detached from the surrounding normal tissue after PTT treatment, leading to a comprehensive cure. These results suggest that photostable and biocompatible ternary copolymer nanoparticles based on PDTT-253 show promise for PTT therapy in brain tumors through in situ injection and NIR irradiation. STATEMENT OF SIGNIFICANCE: A molecular design strategy was developed to create a series of ternary copolymers by incorporating various π-conjugated molecules into the conjugated skeleton. Through this approach, PDTT-253, with rational molar contents of three units and a relatively minor twisted architecture between donors and π-bridges, demonstrated enhanced near-infrared (NIR) absorbance and photothermal conversion efficiency of 85.1 % at 808 nm. Furthermore, PDTT-253 nanoparticles exhibited exceptional photothermal stability, high biocompatibility, and strong NIR photothermal killing efficacy against U87 cells. Following the injection of PDTT-253 NPs into U87 glioma-bearing mice, a single 808 nm laser irradiation treatment resulted in the inhibition of glioma growth, with the ablated glioma being entirely detached from the surrounding normal tissue after photothermal therapy treatment, leading to a comprehensive cure.

Light‐Driven Dynamic Defect‐Passivation for Efficient Inorganic Perovskite Solar Cells

AbstractDue to its soft lattice characteristics, all‐inorganic cesium lead halide (CsPbI3‐xBrx) perovskite is vulnerable to external environmental stress such as moisture, polar solvent, illumination. resulting in structural defects (VI, Ii, etc.) and ion mobility. However, most of the prior arts focus on short‐term and static passivation, which has a negligible effect on defects formed during solar cell operation. Herein, a photoisomerizable molecule, 1,3,3‐trimethylindolino‐8′‐methoxybenzopyrylospiran (OMe‐SP), exhibiting light‐driven pre‐isomeric (SP) and post‐isomeric (PMC) configurations, is employed as an interfacial protective layer on top of CsPbI3‐xBrx. The present strategy not only effectively suppresses migration of halogen ions, but also enables sustainable passivation of defects, thereby significantly reducing interfacial charge recombination and retarding perovskite degradation. Consequently, the OMe‐SP‐modified perovskite solar cells (PSCs) exhibit superior stability, maintaining 91% of their initial efficiency after aging 1032 h under maximum power point (MPP) tracking and continuous one sun illumination. Meanwhile, the OMe‐SP‐modified cell also achieves an impressive power conversion efficiency of 22.20%, which stands as the highest among all‐inorganic perovskite solar cells. Overall, the implementation of this robust strategy provides sustainable defect passivation and continuous suppression of ion migration for achieving both high PCE and stable inorganic perovskite.

Biomass-Derived Materials in Perovskite Solar Cells: Recent Progress and Future Prospects.

As a promising photovoltaic (PV) technology, perovskite solar cells (PSCs) have made significant progress in attaining high PCE, while challenges remain regarding stability and low cost. Conventional PSCs using noble metals (e. g., Au and Ag) as back electrodes and transparent conducting oxides as front electrodes contribute significantly to their high costs. PSCs comprising biomass-derived materials, such as biocarbon as back electrodes and flexible and transparent cellulosic substrates as front electrodes, offer a promising solution to address these issues. These approaches have the potential to simultaneously improve stability and decrease manufacturing costs, making PSCs closer to commercialization. This review article furnishes a comprehensive overview of recent developments in biocarbon-based perovskite solar cells (C-PSCs), focusing on various biomass-derived biocarbon materials utilized as back electrodes in different C-PSCs device structures. This article also compiles the advancement of flexible and transparent cellulosic substrate-based PSCs by highlighting the fundamentals of PSC and C-PSC architectures, the basics of biomass, and the synthesis of biocarbon. Finally, this review discusses the current challenges and future research directions for optimizing biocarbon materials and cellulosic substrates in PSC technology.

Highly Stable Near-Infrared II Luminescent Diradicaloids for Cancer Phototheranostics.

Near-infrared II (NIR-II) phototheranostic agents have become prominent agents for the early diagnosis and precise treatment of cancer. Organic open-shell diradicaloids with distinct structure and narrow band gap are promising candidates for phototherapeutic agents due to their strong spin-coupling effect and NIR light-harvesting capacity. However, achieving stable and efficient NIR-II luminescent diradicaloids is crucial yet rather challenging considering their high chemical reactivity and self-absorption. Herein, two highly stable NIR-II luminescent diradicaloids, 2PhNVDPP and PhNVDPP, were successfully fabricated by employing an acceptor planarization/π-conjugation extension and donor rotation strategy. After encapsulation into water-dispersible nanoparticles (NPs), 2PhNVDPP NPs exhibit NIR-II luminescence, high PCE of 53%, and improved photo/heat stability. In vivo experiments with 2PhNVDPP NPs demonstrated the clear visualization of blood vessels and tumors, as well as the successful NIR-II imaging-guided photothermal ablation of tumors. This study not only develops a pioneering stable diradicaloid phototherapeutic agent with NIR-II luminescence but also provides a unique perspective for the effectiveness of multimodal anticancer therapy.

Tetrabutylammonium Hydroxide-Functionalized Ti3C2Tx MXene for Significantly Improving the Photovoltaic Performance of Perovskite Solar Cells.

An appropriate electron transport layer (ETL) or cathode buffer layer (CBL) is critical for high-performance perovskite solar cells (PVSCs). In this work, tetrabutylammonium hydroxide (TBAOH)-functionalized Ti3C2Tx MXene (TBAOH-Ti3C2Tx) is developed to improve the photovoltaic performance of PVSCs. TBAOH-Ti3C2Tx is synthesized by HF etching and then TBAOH intercalation, and TBAOH can effectively attach to the Ti3C2Tx surface during the intercalation process. In hole transport material (HTM)-free carbon-based PVSCs with the structure of ITO/ETL/MAPbI3/carbon, the SnO2 doped by TBAOH-Ti3C2Tx (SnO2:TBAOH-Ti3C2Tx) as ETL shows decreased WF and increased conductivity and improves the growth of the perovskite film with a larger grain and significantly reduced defects, which synergistically facilitate charge transport and extraction and reduce charge recombination. The HTM-free carbon-based PVSC with SnO2:TBAOH-Ti3C2Tx ETL exhibits a significantly higher PCE of 14.93% with enhanced device stability compared to the control device with pristine SnO2 ETL (11.95%) and also outperforms most of the HTM-free carbon-based PVSCs with MAPbI3 perovskite reported so far. In traditional inverted PVSCs with the structure of ITO/PTAA/MAPbI3/PCBM/CBL/Ag, the TBAOH-Ti3C2Tx is utilized as a CBL to significantly enhance device performance with a high PCE of 21.16%, which is obviously superior than that (16.26%) of the control device without CBL. The impressive results indicate that tetrabutylammonium hydroxide-functionalized Ti3C2Tx MXene possesses great application potential in different functional layers for high-performance PVSCs.

Flexible Narrow Bandgap Sn-Pb Perovskite Solar Cells with 21% Efficiency Using N,N'-Carbonyldiimidazole Treatments.

Flexible tin-lead (Sn-Pb) mixed perovskite solar cells (PSCs) are among the promising flexible photovoltaics, owing to the narrow bandgap (NBG) of Sn-Pb perovskites, flexible and wearable features, and their role as a critical component in all-perovskite tandem photovoltaics. However, the flexible Sn-Pb PSCs suffer from a low power conversion efficiency, no higher than 18.5%, along with limited stability. Herein, we reported an efficient and stable flexible NBG Sn-Pb PSC via an N,N'-carbonyldiimidazole (CDI) passivation strategy. CDI, with strong adsorption energy, preferentially binds to Sn2+ compared with oxygen (O2), thus effectively inhibiting the adsorption of O2 on perovskite surfaces. The transfer of electron density around Sn2+ dramatically decreased, thus suppressing Sn2+ oxidation. The CDI treatments endowed the Sn-Pb mixed films with fewer defects, improved crystallinity, better morphology, and matched energy-level alignment. The flexible Sn-Pb devices exhibited a high PCE of 21.02%. Besides, the devices showed enhanced stability and promoted flexibility. This work provides a pathway to visibly increase the efficiency and stability of the flexible Sn-Pb mixed photovoltaic cells.

Achieving High Doping Density in pH-neutral Conjugated Polyelectrolyte Toward Effective Hole-Transporting Materials for Organic Solar Cells.

The lack of effective and non-corrosive hole-transporting layer (HTL) materials has remained a long-standing issue that severely restricts the performance of organic solar cells (OSCs). Most pH-neutral conjugated polyelectrolytes (CPEs) exhibit inferior performance to the acid-doped HTL materials due to their low doping density. In this study, a series of pH-neutral CPEs is designed and synthesized with high doping density as HTL materials. Through an elaborate synthetic route, two sulfonate-terminating alkoxyl side chains can be introduced into thiophene, by which the electron-rich, highly soluble, and chemically stable thiophene monomer is synthesized to enable the subsequent polymerization. The CPE PTT-F exhibit a remarkable self-doping property with an enhanced doping density from 2.01 × 1017 to 7.02 × 1018 cm-3. The high work function and the increased doping density of PTT-F-based HTL decrease the depletion region width from 38.4 to 8.1nm at the anode interface, which minimized the energy loss in hole transport. Consequently, a binary OSC modified by PTT-F-based HTL achieve a high PCE of 18.8%. To the best of the knowledge, this is the highest PCE for OSC employing CPE-based HTL. The results from this work demonstrate an encouraging achievement of realizing exceptional hole collection ability in pH-neutral CPEs.

3-Methylthiophene: A Sustainable Solvent for High-Performance Organic Solar Cells.

The use of harmful halogenated or aromatic solvents such as chloroform (CF), chlorobenzene (CB), and o-xylene (o-XY) is one of the greatest barriers to the industrial-scale manufacturing of high-performance organic solar cells (OSCs). Therefore, it is necessary to eliminate the effects of these solvents to ensure practical feasibility of OSCs. We found that the anthracene-terminated polymer donor and small-molecule acceptor BO-4Cl had good solubility in 3-methylthiophene (3-MeT). There were no toxicity labels in the SDS and exposure control limits for 3-MeT. An overall power conversion efficiency of 16.87% was achieved by using 3-MeT as the solvent for solar cell fabrication, which was higher than that of the cells made from CF (16.18%) and o-XY (15.69%). The best OSC based on PM6:D18:L8-BO and fabricated with 3-MeT exhibited a high PCE of 18.13%, which is one of the highest values for cells fabricated from halogen-free solvents. These results indicate that 3-MeT is an eco-friendly and low-toxicity solvent for the sustainable fabrication of the OSC active layer.

Electronic regulation by constructing RGO/MoCQD/CF double interface to enhance performance in solar cells

The intrinsic defects such as the low electrical conductivity and sluggish kinetics for counter electrode seriously hinder its ability to meet the requirements of daily applications for dye-sensitized solar cells (DSSCs). Herein, to propel the development of DSSCs toward ultra-high stability and fast dynamics, the counter electrode (CE) of RGO/MoCQD/CF nanoreactors are created by sandwiching stable MoC quantum dots (QDs) in two distinct carbon matrices {Reduced Graphene Oxide (RGO) and Carbon Flower (CF)}. The multi-structured nanoreactors both effectively enhance stability of catalysis by forming sandwich structure and offers homogeneous dispersion of MoCQD to avoid its agglomeration. Numerous electrons assemble at the RGO contact, which can disrupt the balanced charge state and and modify the electronic structures of Mo sites to expedite reaction kinetics and I3- catalytic activity, according to studies using density functional theory and X-ray photoelectron spectroscopy. Additionally, the framework also contains the advantage of the vast uniformly dispersed active sites, a fast ion–electron transportation channel, and reactive structures that facilitate electrolyte infiltration. By virtue of integration of multiple advantages, DSSC with RGO/MoCQD/CF CE brings excellent performance, i.e., high PCE (9.08 %) and ultra-long cycling performance (96 h), offering great potential for make use of basically viable DSSC.

Layer‐by‐Layer All‐Polymer Solar Cells Approaching 19% with Dual‐Donor Modulation of an Interpenetrating Network

AbstractAll‐polymer systems are promising for commercial applications because the lower diffusivity of polymers helps to inhibit the large‐scaled phase separation and obtain excellent stability. Achieving a fine‐tuned morphology of the active layer with an appropriate vertical phase has long been a major goal in obtaining efficient all‐polymer solar cells (all‐PSCs). Herein, through the synergistic effect of layer‐by‐layer (LBL) structure and dual donor strategy, high performance and stable all‐PSCs are prepared by constructing an interpenetrating network. The introduction of the third component PTzBI‐dF suppresses excessive aggregation and reduces exciton recombination. The formation of a favorable p‐i‐n structure helps to adjust the vertical phase distribution and improve stability. Ultimately, through the fine optimization, PBQx‐T‐Cl:PTzBI‐dF/PY‐IT achieves a high PCE of 18.83%. This research demonstrates a simple and effective way to construct high‐performance OSCs by desirable active layer morphology and vertical phase distribution.

Highly efficient halogen-free rigid and flexible binary organic solar cells using new solid indacene additive

Flexible Organic solar cells (OSCs) have garnered widespread attention due to the increased popularity of wearable electronic devices. To enhance the efficiency and stability of the device we have prepared (2E,2′E)-3,3'-(4,4,9,9-tetrahexadecyl-4,9-dihydro-s-indaceno[1,2-b:5,6-b'] dithiophene-2,7-diyl)bis(2-cyanoacrylic acid) (IDT) based dopant by reacting the aldehyde precursor with cyanoacetic acid in the presence of piperdine. Here, we investigate the effect of IDT on the performance of OSCs by adding IDT to star active layers PM6:Y6 and PM6:BTP-eC9 to improve OSCs' performance through morphology optimization. The addition of 5 wt% IDT significantly improved the device performance, achieving a remarkable PCE of 16.08 % for PM6:Y6 devices. The charge transport and recombination dynamics analysis showed that the appropriate concentration of IDT can provide better channels for carrier transport, promoting effective charge generation and extraction in OSCs. It is observed that the addition of IDT promotes effective generation and dissociation of excitons, thus improving OSC performance. The flexible ITO-free OSC was fabricated using PM6:Y6:IDT as the active layer film, achieving a high PCE of 12.59 % with VOC, JSC, and FF of 0.83 V, 23.21 mA/cm2 and 68.63 %, respectively. Hence, the findings indicate a reliable approach which could potentially deliver rigid and flexible OSCs with excellent performance and commercial viability.

Efficiency improvement of CsSnI3 based heterojunction solar cells with P3HT HTL: A numerical simulation approach

Recently, lead free CsSnI3 based solar cells are gaining popularity among researchers due to their outstanding semiconducting characteristics. To improve the efficiency of the recently suggested ITO/ZnMgO/CsSnI3/P3HT/Au solar cell and examine the effects of the five HTL such as (P3HT, PEDOT:PSS, PTAA, MoO3, CFTS) and ZnMgO as ETL via SCAPS-1D on key performance indicators like PCE, FF, JSC and VOC is the main purpose of this works. The effects of thickness variation, carrier density, each layer’s interface defect, bulk defect density, operating temperature, and front and rear electrode placement have been studied. The PCE, VOC, JSC, and FF have shown 7.03 %, 0.32 V, 33.76 mA/cm2, and 62.50 %, respectively with reference structure’s (ITO/ZnMgO/CsSnI3/Au). The highest PCE, VOC, JSC, and FF is improved to 17.04 %, 0.67 V, 35.61 mA/cm2, and 71.39 %, respectively by adding P3HT layer as a HTL with proposed structures (ITO/ZnMgO/CsSnI3/P3HT/Au) then other four HTL (PEDOT:PSS, PTAA, MoO3, CFTS).

“Mutually Doped” Conjugated Polyelectrolyte‐Polyoxometalate Complex as Hole Transporting Material for Efficient Organic Solar Cells

Comprehensive SummaryCompared to electron transporting layer materials, the species and numbers of hole transporting layer (HTL) materials for organic solar cells (OSCs) are rare. The development of HTL materials with excellent hole collection ability and non‐corrosive nature is a long‐standing issue in the field of OSCs. Herein, we designed and synthesized a series of conjugated polyelectrolytes (CPEs) with continuously varied energy levels toward HTL materials for efficient OSCs. Through a “mutual doping” treatment, we obtained a CPE composite PCT‐F:POM with a WF of 5.48 eV and a conductivity of 1.56 х 10–3 S/m, meaning that a good hole collection ability can be expected for PCT‐F:POM. The OSC modified by PCT‐F:POM showed a high PCE of 18.0%, which was superior to the reference device with PEDOT:PSS. Moreover, the PCT‐F:POM‐based OSC could maintain 91% of the initial PCE value after storage of 20 d, meaning that the long‐term stability of OSCs is improved by incorporating the PCT‐F:POM HTL. In addition, PCT‐F:POM possesses good compatibility with large‐area processing technique; i.e., a PCT‐F:POM HTL was processed by the blade‐coating method for fabricating 1 cm2 OSC, and a PCE of 15.1% could be achieved. The results suggest the promising perspective of PCT‐F:POM in practical applications.

Theoretical simulation of mixed organic–inorganic perovskite solar cell using SCAPS-1D simulator

In this work, a triple cation mix halide perovskite solar cell is explored to improve its stability and efficiency. FTO/SnO2/perovskite/CuSCN/carbon the device structure is simulated using SCAPS-1D and outcomes and found in good agreements with experimental results. Furthermore, the effect of various parameters like absorbance coefficient, reflection of front surface, defect capture cross section and defect position on device performance are examined. This optimized device exhibits high PCE, 27.10 % with Voc = 1.24 V, Jsc = 25.37 mA/cm2 and FF = 85.70 %. Finally, the effects of temperature, absorber defect density and interface defect density are computed on optimised structure and observed degradation in device performance with increase in these factors. Lastly, the results are concluded using J-V and EQE curves. This study may be vital in the development of stable and highly efficient triple cation perovskite solar cell technology.

Revealing Interaction of Fluorinated Propylamine Hydrochloride with Precursor and Defect States of Perovskite Films Toward Efficient Flexible Solar Cells

AbstractThe trap state at the surfaces and grain boundaries of perovskite is one of the major obstacles to the further commercialization of flexible perovskite solar cells (FPSCs). Herein, two innovative multifunctional fluorinated propylamine salt 2,2,3,3,3‐pentafluoropropylamine hydrochloride (PFPACl) and 3,3,3‐triflupropylamine hydrochloride (TFPACl) are in situ introduced onto the photo absorbing layer to improve the performance of the FPSCs. The nuclear magnetic resonance (NMR) spectroscopy indicates strong interactions of both PFPACl and TFPACl with the perovskite precursor components. For the first time, the structures of the supramolecular complexes formed by two additives with FAI are deduced from NOESY NMR data, thus pointing to the importance of the preorganization of the perovskite components in solution before film casting. The experiments and density functional theory（DFT) calculations reveal that PFPACl is likely dissociated more into the form of R‐NH3+‐Cl− due to the higher electronegativity of the fluoroalkyl tail. Therefore, PFPA+ binds more strongly to VFA defects than TFPA+, and anion Cl− has strong enough interaction with VFAI and uncoordinated Pb2+, leading to homogeneous coverage of PFPACl on the entire surface of the perovskite films and better energy alignment with the hole transport layer. Consequently, PFPACl‐treated FPSCs achieved a relatively high PCE of 23.59% with excellent mechanical robustness and operational stability.

Developing Benzodithiophene-Free donor polymer for 19.36% efficiency Green-Solvent-Processable organic solar cells

In this work, a newly benzodithiophene-free D-A polymer donor, named PDTP-BDD, was developed for realizing green-solvent processed high-performance OSCs. By bridging two electron-rich unit of dithieno[3,2-b:2′,3′-d]pyridin-5(4H)-one (DTP) and electron-deficient benzo[1,2-c:4,5c′]dithiophene-4,8-dione (BDD) with thiophene units, PDTP-BDD possesses high absorption in the short wavelength range and a deep HOMO energy level. The rigid building blocks also make PDTP-BDD has strong aggregation and poor solubility in common halogen-free solvents (such as o-xylene) at room temperature, but it is readily dissolved and disaggregated at high temperature (120 °C). After cooling down to a lower temperature (60 °C), PDTP-BDD self-assembled and pre-aggregated slowly in the solution at a long time. By employing a delayed processing strategy in the layer-by-layer processed OSCs (LbL-OSCs), an optimized fibril network of the underling layer was realized, enabling the permeation of acceptor into the donor network. The optimized PDTP-BDD/L8-BO-based LbL-OSCs realized a high PCE of 18.42 %. By adding a small amount of D18 to further optimize the PDTP-BDD fibril network, an impressive PCE of 19.36 % was achieved finally in the resulting ternary LbL-OSCs, which is the highest value for OSCs processed by halogen-free solvents.

Dipoles with donor-π-acceptor structure inhibit ion migration to improve the efficiency and stability of inverted perovskite solar cells

Organic-inorganic hybrid perovskites (PVK) have aroused big enthusiasm of many researchers due to their excellent photoelectric properties. However, PVK films always inevitability demonstrate large number of defects, thus greatly affect the performance and stability of the device. Many parts of the defects are aroused from ion migrations because of the weak antibonding between Pb and I. Here, we use 4-Amino-3,5-difluorobenzonitrile (AFBN) to regulate the light-absorbing layer of perovskite films. The AFBN molecules with donor-π-acceptor (D-π-A) structure can simultaneously interact with MA+/Pb2+ cations and I- anions in PVK, which can validly inhibit ion migration and effectively restrain non-radiative recombination, thus improves the photoelectric performance of inverted perovskite solar cells (i-PSCs). The AFBN-based device achieved a champion efficiency of 18.55%, which is a high PCE for inverted PSCs with simple structure of FTO/NiOx/perovskite/PCBM/BCP/Ag and for devices with relatively high band gap of 1.62 eV, while the control one only shows an efficiency of 16.37%. Meanwhile, the modified devices demonstrate excellent humidity stability. This work provides a new path for dipoles with donor-π-acceptor structure to inhibit ion migrations for improved efficiency and stability of reverse PSCs.