Conversion Efficiency Of Solar Cells Research Articles

Manipulating Aggregation Kinetics toward Efficient All-Printed Organic Solar Cells.

The power conversion efficiencies (PCEs) of all-printed organic solar cells (OSCs) remain inferior to those of spin-coated devices, primarily due to morphological variations within the bulk heterojunction processed via diverse coating/printing techniques. Herein, cyclohexyl is introduced as outer side chains to formulate a non-fullerene acceptor, BTP-Cy, aimed at modulating the molecular aggregation in solution and subsequent film formation kinetics during printing. Investigations demonstrate that BTP-Cy molecule with cyclohexyl side chains exhibits enhanced intermolecular π-π stacking, optimal solution aggregation size, and favorable phase separation. Consequently, PB3:FTCC-Br:BTP-Cy-based OSCs achieve remarkable PCEs of 20.2% and 19.5% via spin-coating and blade-coating, respectively. Furthermore, a 23.6 cm2 module exhibits a remarkable efficiency of 16.7%. This study offers a fresh perspective on tailoring the film formation kinetics of photoactive materials during printing through molecular design, paving a novel path to enhance the efficiency of all-printed OSCs.

A Lightweight Hydrogel System for Passive Cooling of Solar Cells

AbstractThe power conversion efficiency (PCE) of photovoltaics (PVs) or solar cells is significantly affected by the temperature. Under 1‐sun solar irradiance, the PV temperature can reach up to 65–70 °C; consequently, the PCE and power output can be reduced by as much as 18%. Herein, highly efficient PV passive cooling based on thermoresponsive poly(N‐isopropylacrylamide) (PNIPAM) semi‐interpenetrating polymer networks (semi‐IPNs) containing poly(vinyl alcohol) (PVA), poly(ethylene glycol) (PEG), or polyacrylamide (PAM), is demonstrated. Crucially, the measurements of water release ratio and differential thermal analysis (DTA) reveal that the cooling performance of hydrogels not only depends on how much water they absorb but also on how fast they can release water. The DTA experiments allow the quantification of specific cooling power (SCP). The optimal composition of PNIPAM/PAM hydrogels with 15 wt.% PAM shows the largest swelling ratio of 30 and highest SCP of 1.86 W g−1. Employed in the cooling application of silicon PV cells, a large temperature reduction of 23 °C is achieved (from 70 to 47 °C), resulting in a relative increase in PCE by 12.3%. Remarkably, only 5.1 kg m−2 of the hydrogels is required, 90% lower than what is typically required of phase change materials for passive PV cooling.

Theoretical Analysis of Power Conversion Efficiency of Lead-Free Double-Perovskite Cs2TiBr6 Solar Cells with Different Hole Transport Layers

In recent years, there has been significant investigation into the high efficiency of perovskite solar cells. These cells have the capacity to attain efficiencies above 14%. As the perovskite materials that include lead pose a substantial environmental risk, components that are free from lead are used during the process of solar cell development. In this work, we use a lead-free double-perovskite material, namely Cs2TiBr6, as the main absorbing layer in perovskite solar cells to enhance power conversion efficiency (PCE). This work is centered on the development of solar cell structures with materials such as an ETL (electron transport layer) and an HTL (hole transport layer) to enhance the PCE. In this theoretical work, we perform simulations and analysis on double-perovskite Cs2TiBr6 to assess its efficacy as an absorber material in various HTLs like Cu2O and CuI, with a fixed ETL of C60 using SCAPS (Solar Cell Capacitance Simulator, SCAPS 3.3.10) Software. This is a one-dimensional solar cell simulation program. In this work, the thickness of the double-perovskite material is also varied between 0.2 and 2.0 µm, and its efficiency is observed. The effect of temperature variation on efficiency in the range of 300 K to 350 K is observed. The effect of defect density on efficiency is also observed in the range of 1 × 1011 to 1 × 1016. In this theoretical work, perovskite solar cells, including their absorbing layer, demonstrate outstanding ETLs and HTLs, respectively. As a result, the cells’ achieved PCE is improved. This work demonstrates the effectiveness of this lead-free double-perovskite structure that absorbs light in perovskite solar cells.

Enhancing Efficiency of Lead‐Free Cs2TiIxBr6‐x Perovskite Solar Cells Through Linear and Parabolic Grading Strategies: Toward 31.18% Efficiency

ABSTRACTThe most amazing environmentally friendly energy source is solar energy, which can be captured with the aid of photovoltaic (PV) cells. Perovskite solar cells (PSCs) that are hybrid (organic–inorganic) have demonstrated remarkable PV ability. The advantages of halide‐based perovskite are numerous and include cheap cost, high efficiency, and simplicity in fabrication. Due to their poisonous nature, lead (Pb)‐based PSCs often pose a concern to the environment. They also have other drawbacks, such as stability problems, problems with scalability, and health risks associated with Pb exposure. Thus, the primary intent of this study is to examine the Pb‐free, inorganic titanium‐based perovskite complex Cs2TiIxBr6‐x, which serves as the active layer. When compared with other elements, titanium is nontoxic, strong, affordable, and easily accessible. To improve the efficiency of lead‐free (Au/CuSbS2/Cs2TiIxBr6‐x/CdS/FTO) device structure, both linear and parabolic grading methods are used in the simulation. The perovskite composition Cs2TiIxBr6‐x is a mixed halide system, with different amounts of iodine (I) and bromine (Br) ions integrated into the crystal lattice. Within the halide system, “x” indicates the percentage of iodide ions that replace bromide ions. Light absorption and energy conversion efficiency in solar cells may be maximized by fine tuning the material's band gap by varying “x,” which can range from 0 to 6. When the active layer is graded linearly, the band gap is adjusted by adjusting the composition x, which ranges from 0 to 6, throughout the active layer's thickness. The bending factor changes from 0 to 1 in the case of parabolic grading of the Cs2TiIxBr6‐x layer, indicating an enhancement in the device's PCE as a result of high wavelength photon absorption. Our simulations show a significant improvement in PCE, with an astounding result of 31.18% for parabolic grading, a 7.93% increase above PCE from linear grading, which is 28.89%. Other noteworthy metrics that exhibit exceptional outcomes include JSC 34.36 mA.cm−2, FF 86.81%, and VOC 1.0452 V. The stability in the output of the device in the realistic temperature range confirms the highly stable nature of the proposed PSC device. These results show how effectively our approach improves the efficiency and effectiveness of Pb‐free PSC's. As we are interested in this realistic environmental temperature range of the whole world, we proposed that Cs2TiIxBr6‐x‐based PSCs are highly suitable and stable for the real‐time experiment, which is the need of PSCs nowadays.

Rhodanine Substitution of Asymmetric Nonfullerene Acceptors for High-Performance Organic Solar Cells.

Asymmetric substitution is acknowledged as a straightforward yet potent approach for the optimization of small molecule acceptors (SMAs), thereby enhancing the power conversion efficiency (PCE) of organic solar cells (OSCs). In this work, we have successfully engineered and synthesized a novel asymmetric SMA, designated as Y6-R, which features a rhodanine-terminated inner side-chain. In devices with PM6 as the polymer donor, the asymmetric Y6-R demonstrated an impressive PCE of 18.62% with an open-circuit voltage (Voc) of 0.863 V, a short-circuit current (Jsc) of 27.89 mA cm-2, and a fill factor (FF) of 77.35%, which is much higher than that of the symmetric SMA Y6-based devices (16.84%). The superior performance for PM6:Y6-R devices can be attributed to a combination of factors, including the upshifted LUMO energy levels, more desired exciton dissociation, collection, and extraction capability, as well as reduced recombination and suppressed Eloss. In addition, the Y6-R molecules promote the more desired coaggregation behaviors along with the donor, endowing the stronger and more ordered crystallinity of blend films. Our findings underscore the effectiveness of rhodanine-substitution, as a representative of "A" units, of the asymmetric SMAs in fine-tuning the coaggregation behavior with the donor, thereby enhancing crystallinity and efficiency.

Enhanced Efficiency and Stability in Blade-Coated Perovskite Solar Cells through Using 2,3,4,5,6-Pentafluorophenylethylammonium Halide Additives.

The power conversion efficiency (PCE) of perovskite solar cells is sensitive to their method of fabrication as well as the combination of materials in the perovskite layer. Air knife-assisted blade coating enables good quality perovskite films to be formed but the device efficiencies still tend to lag behind those fabricated using spin-coated perovskite layers. Herein we report the use of three 2,3,4,5,6-pentafluorophenylethylammonium halides (FEAX, where X = I-, Br- or Cl-) as additives in nitrogen knife-assisted blade-coated methylammonium lead iodide (MAPbI3) perovskite solar cells. The additives were all found to passivate defects in the MAPbI3 films. The use of chloride as the counteranion led to additive containing films with the largest crystal size and fewest defects and consequently the FEACl film was found to have the highest photoluminescence (PL) intensity, longest average PL lifetime and lowest trap density. These features led to the devices having a high open-circuit voltage (Voc) of 1.17 V and a PCE of 21.4%. In addition, the hydrophobic fluorinated cations led to the additive containing devices being more stable, with those containing FEACl having the best thermal stability and performance under maximum-power-point (MPP) tracking in a humid (≈65%) environment at 50 ± 1 °C.

Why Sb2Se3/CdS Interface Produces Higher Power Conversion Efficiency.

Developing the Cd-free electron transport layer (ETL) is a crucial subject in the field of antimony selenide (Sb2Se3) solar cells. At present, the power conversion efficiency (PCE) of the Cd-free Sb2Se3 solar cell is still substantially lower than that of CdS-based devices. It is significant to reveal the electron transfer features in Sb2Se3/CdS heterojunction and Sb2Se3/Cd-free ETL heterojunction for development of a Cd-free Sb2Se3 solar cell with high PCE. In this work, Sb2Se3/Cd heterojunction and Sb2Se3/ZnO heterojunction were systematically investigated from the view of PCE, trap state passivation, interface charge separation, and carrier kinetics on a picosecond time scale. Experimental results demonstrate that electron transfer at Sb2Se3/CdS and Sb2Se3/ZnO occurs on a comparable time scale with time constants of 1.38-3.42 and 1.91-3.17 ps, respectively. The PCE gap between the Cd-based device and the Cd-free device is mainly determined by the passivation effect. The excellent passivation effect of CdS on Sb2Se3 ensure the high electron transfer efficiency at Sb2Se3/CdS heterojunction. Our results reveal the key challenges in improving the performance of Cd-free Sb2Se3 solar cells.

Stable and Efficient Perovskite Photovoltaics via a Three‐In‐One Passivating Approach by Aminoacetonitrile Hydrochloride

AbstractReducing defect density is of significant importance for enhancing the power conversion efficiency (PCE) and stability of perovskite solar cells (PSCs). While most previous outstanding studies have focused on individual layers within the perovskite device structure. Herein, a three‐in‐one strategy using the aminoacetonitrile hydrochloride (AmiHCl) molecule to reduce the defects in the bulk and surface of perovskite. The results of the study found that the AmiHCl bottom modification can decrease the number of buried interface holes, doping into bulk perovskite can modulate crystallization via a strong interaction between AmiHCl and perovskite components, and the upper interface modification can inhibit the formation of vacancies by creating hydrogen bonds with A‐site cations. This approach yields PSCs with an efficiency of 25.90% and a high fill factor (FF) of 88.54%. Additionally, the modified PSCs show significantly enhanced operational stability, with the PCE retaining more than 90.0% of the initial value after 1350 h of maximum power point tracking.

The role of TCNQ for surface and interface passivation in inverted perovskite solar cells

The noticeable growth in the power conversion efficiency of solution-processed organo-inorganic halide perovskite solar cells (OIHPSCs) incited the photovoltaic community to look for limitations that hurdle the commercialization process. The surface and interface defects between the perovskite and electron transport layers are among the main challenges that cause significant non-radiative recombination losses, thereby they result in poor performance and stability. In this work, tetracyanoquinodimethane (TCNQ), a strong electron acceptor molecule, is applied at the interface between the photoactive perovskite and [6,6]-phenyl C61 butyric acid methyl ester (PCBM) layers to modify the interface, and enhance device performance and stability. Steady-state and time-resolved photoluminescence measurements were used to characterize the role of the TCNQ passivation in reducing non-radiative recombination of charge carriers. Current density versus voltage (J-V) measurements show improvement in devices open-circuit voltage (Voc), short-circuit current density (Jsc), and fill factor (FF) for devices with TCNQ interface passivation, which is attributed to suppressed non-radiative recombination. In addition, a noticeable improvement in the device’s stability was observed. This study reveals the dual role of TCNQ passivation in improving the photoelectric properties and stability of ambient air processed perovskite devices with the pin architecture.

Reducing Parasitic Loss and Deep Defect Formation via Copper Doping Toward Highly Efficient Sb2Se3 Solar Cells

AbstractAntimony selenide (Sb2Se3) has great potential as a light‐absorbing layer in thin‐film photovoltaics because of its excellent photoelectric properties and superior stability. Presently, high‐efficiency Sb2Se3 solar cells use a heterojunction consisting of a p‐type Sb2Se3 absorber and an n‐type CdS layer. The power conversion efficiency (PCE) of Sb2Se3 solar cells is restricted by the low carrier concentration in the CdS layer, complex intrinsic deep defects of Sb2Se3, and unsuitable energy level band alignment in the junction. This paper presents a copper (Cu) doping strategy that achieves a synergistic doping effect, enabling controllable doping in both the n‐type CdS layer and p‐type Sb2Se3 absorber. First, proper Cu doping significantly enhances the short‐wavelength transmittance of CdS films and increases their n‐type carrier concentration. The Vbi in the CdS/Sb2Se3 heterojunction improves from 521 to 751 mV. Second, a post‐annealing process is performed to facilitate Cu diffusion from the CdS layer to the Sb2Se3 absorber. This approach successfully passivates intrinsic deep defect E2 and reduces the interfacial trap‐assisted nonradiative recombination losses. As a result, the Cu‐doped Sb2Se3/CdS solar cell presents a PCE of 10.23%, representing a 40% enhancement in PCE compared to the undoped CdS/Sb2Se3 heterojunction device.

Enhancing charge carrier dynamics with an N-type polymer guest for printable ternary organic solar modules

The ternary strategy offers a promising route to enhance the power conversion efficiencies (PCEs) of organic solar cells (OSCs). In this contribution, we focus on the state-of-the-art binary system PM6:L8-BO and reveal how the n-type polymer guest (PYIT) in the PM6:L8-BO:PYIT ternary system enhances carrier dynamics, thereby improving both efficiency and scalability for large-area printable OSC modules. These benefits are primarily attributed to two key factors: (i) the excellent miscibility of the PYIT guest with the host materials, coupled with the chain-dominant structure and high crystallinity nature of the PYIT polymer, which creates additional pathways for carrier transport and charge transfer; (ii) the incorporation of PYIT, which limits the excessive aggregation of L8-BO, improves molecular packing, and reduces film defects, thereby enhancing exciton dynamics. These optimizations lead to an increase in PCEs from 17.58% in the binary system to 18.59% in the ternary OSC, with improvements across all photovoltaic parameters. More importantly, the PM6:L8-BO:PYIT ternary system exhibits excellent compatibility with large-area printing processes, as demonstrated by a doctor blading OSC module achieving 15.57% PCE over an area of 11.7 cm2. This work highlights the potential of the ternary methodology in tuning the physical properties of OSCs while enhancing both performance and scalability.

Mitigating the Efficiency Deficit in Single-Crystal Perovskite Solar Cells by Precise Control of the Growth Processes.

The power conversion efficiencies (PCEs) of polycrystalline perovskite solar cells (PC-PSCs) have now reached a plateau after a decade of rapid development, leaving a distinct gap from their Shockley-Queisser limit. To continuously mitigate the PCE deficit, nonradiative carrier losses resulting from defects should be further optimized. Single-crystal perovskites are considered an ideal platform to study the efficiency limit of perovskite solar cells due to their intrinsically low defect density, as demonstrated in bulk single crystals. However, current single-crystal perovskite solar cells (SC-PSCs) based on single-crystal thin film (SCTF) suffer from severe nonradiative carrier losses at the interface and in the bulk simultaneously due to the immature SCTF growth techniques. In this study, we show that the SC-PSCs can outperform state-of-the-art PC-PSCs, with MAPbI3 as an example, by suppressing carrier losses at the interface and in the bulk in device-compatible SCTFs through precisely controlling their growth.

A High Throughput Platform to Minimize Voltage and Fill Factor Losses

AbstractOrganic photovoltaics (OPV) now can exceed 20% power conversion efficiency in single junction solar cells. To close the remaining gap to competing technologies, both fill factor and open‐circuit voltage must be optimized. The Langevin reduction factor is a well‐known concept that measures the degree to which charge extraction is favored over charge recombination. It is therefore ideally suited as an optimization target in high‐throughput workflows; however, its evaluation so far requires expert interaction. Here, an integrated high‐throughput workflow is presented, able to obtain the Langevin reduction factor within a few seconds with high accuracy without human intervention and thus suited for autonomous experiments. This is achieved by combining evidence from UV–vis spectra, current–voltage curves, and a novel implementation of microsecond transient absorption kinetics allowing, for the first time, the intrinsic determination of charge absorption cross‐sections, which is crucial to reporting stationary charge densities. The method is demonstrated by varying the donor:acceptor ratio of the high performance OPV blend PM6:Y12. The high reproducibility of the method allows to find a strictly exponential relationship between the PM6 exciton energy and the Langevin reduction factor.

Enhancing power conversion efficiency of polycrystalline silicon solar cells through ZnO/SiO2/Al2O3 anti-reflective coatings via spin coating

The investigation aims to enhance the photocurrent generation of p-Si solar cells through the application of anti-reflective coatings (ARC) including ZnO, SiO2, Al2O3, and a combination of ZnO, SiO2, and Al2O3. The spin coating approach was preferred for depositing anti-reflective coating materials as clear thin films on the substrate of the p-Si cells. The absorbance, reflectance, I-V, morphology, and temperature behaviour of the ARCs onp-Si cells were examined to ascertain the impact of the ARCs. Among several coating materials, the blended ZnO+SiO2+Al2O3on p-Si cells achieved a highest conversion efficiency of 20.71% under controlled setup condition, with anelectrical resistance of5.83×10-3 Ω cm. The examination of the optical characteristics demonstrated a highestabsorbance of 92% and a lowest reflection loss of 10%, attained by the ZnO+SiO2+Al2O3sample within UV band. The ZnO+SiO2+Al2O3 blend exhibited significant enhancement in thermal behaviour, achieving a lowest temperature of 49.9 °C in controlled source settings. Analyses demonstrated that the composite ZnO+SiO2+Al2O3 is a suitable blendwithanideal anti-reflectiveproperties to improve the efficiency of p-Si solar panels.

Machine learning assisted plasmonic metascreen for enhanced broadband absorption in ultra-thin silicon films

We propose and demonstrate a data-driven plasmonic metascreen that efficiently absorbs incident light over a wide spectral range in an ultra-thin silicon film. By embedding a double-nanoring silver array within a 20 nm ultrathin amorphous silicon (a-Si) layer, we achieve a significant enhancement of light absorption. This enhancement arises from the interaction between the resonant cavity modes and localized plasmonic modes, requiring precise tuning of plasmon resonances to match the absorption region of the silicon active layer. To facilitate the device design and improve light absorption without increasing the thickness of the active layer, we develop a deep learning framework, which learns to map from the absorption spectra to the design space. This inverse design strategy helps to tune the absorption for selective spectral functionalities. Our optimized design surpasses the bare silicon planar device, exhibiting a remarkable enhancement of over 100%. Experimental validation confirms the broadband enhancement of light absorption in the proposed configuration. The proposed metascreen absorber holds great potential for light harvesting applications and may be leveraged to improve the light conversion efficiency of ultra-thin silicon solar cells, photodetectors, and optical filters.

Computational investigation of charge transfer mechanisms in dye-sensitized solar cells: unraveling the influence of anchoring groups in 2-styryl-5-phenylazo-pyrrole designed dyes

The proposed dyes demonstrated characteristics conducive to achieving high-power conversion efficiency (PCE) in dye-sensitized solar cells (DSSCs). Novel azo dyes diverse anchoring groups, including carboxylic acid, carboxylic diacid, biscarbodithiolic acid, phosphonic acid, and sulfonic acid, were examined to assess their impact on electronic and optical properties within DSSCs. A computational investigation was conducted to design and evaluate charge transfer mechanisms using azo-pyrrole-based dyes for DSSCs performed with the Gaussians 09 and employing TD-DFT techniques with functions like B3LYP and a 6-31G (d, p) basis set to analyze ground and excited state characteristics. Enhanced charge transfer was observed due to improved molecular properties within DSSCs. The analysis encompassed electronic and optical properties, UV-Vis absorption spectra, light harvesting efficiency, and hardness to elucidate the effects of various anchoring groups. Carboxylic acid-based dyes exhibited broad absorption spectra, the longest maximum wavelength, and the highest light harvesting efficiency, indicating proficient electron injection capabilities.

A metasurface light-trapping structure for solar cell applications.

Light trapping structures can enhance the absorption and reduce the thickness and costs of solar cells. Among light trapping structures, the metasurface structure utilizes Mie scattering to make light enter the solar active layer better, thus improving the photovoltaic conversion efficiency of solar cells. Herein, we simulated and optimized a metasurface light-trapping structure for solar cells and implemented this structure on solar cells. Simulation results of thin-film silicon-based solar cells show that the maximum short-circuit current can be increased to 24.46 mA/cm2 using a metasurface light-trapping structure, which is an increase of 40.49% compared to the reference bare cell. In addition, when this metasurface structure is integrated into a crystalline silicon solar cell, we find that the maximum short-circuits current reaches 29.09 mA/cm2, which is an even more significant improvement of 54.6% compared to the reference bare cell, and the power conversion efficiency increases by 7.14%. This study verifies the effect of a metasurface light-trapping structure on the light absorption of silicon-based solar cells.

Tailored Multisite Rigid Conjugated Molecules to Anchor Perovskite for Comprehensive Management of Perovskite Crystallization and Defects

Abstractengineering has emerged as a promising approach to improve the stability and power conversion efficiency of perovskite solar cells (PSCs) by regulating the crystallization or defects. Conventional methods typically focus on a single functional group, leading to a deficiency in simultaneously addressing the above mentioned two aspects. Here, an innovative approach using (methylsulfonyl)phenyl)prop‐2‐en‐1‐amine hydroiodide (MSPPAI) is presented to concurrently and effectively modulate perovskite crystallization and defect passivation. The unique structure of MSPPAI, combining a rigid conjugated structure with multisite anchoring groups (─NH2 and ─SO2─), enables precise regulation through strong interaction with perovskite components. This interaction promotes the preferred (100) orientation of perovskite crystals, enhances the grain size, and thus improves the film quality. Meanwhile, the conjugated structure and approximate coplanarity further facilitate ordered crystallization and directional growth. Furthermore, by preventing volatile loss and coordinating with residual Pb2+, MSPPAI could effectively stabilize grain boundaries and surfaces to reduce defects and prevent degradation. Utilizing these mechanisms, the corresponding MSPPAI based devices achieves an efficiency of 25.54% and exhibits excellent stability that maintains 93% of its initial efficiency even after 1600 h under humid conditions. This molecular design strategy presents a novel approach for improving the efficiency and stability of PSCs.

Evolution of Two-Dimensional Perovskite Films Under Atmospheric Exposure and Its Impact on Photovoltaic Performance.

Two-dimensional (2D) Ruddlesden-Popper perovskites (RPPs) have garnered significant attention due to their enhanced stability compared with their three-dimensional counterparts. However, the power conversion efficiency (PCE) of 2D perovskite solar cells (2D-PSCs) remains lower than that of 3D-PSCs. Understanding the microstructural evolution of 2D perovskite films during fabrication is essential for improving their performance. This study demonstrates that exposing bare 2D perovskite films to the atmosphere during device fabrication can significantly enhance the PCE of 2D-PSCs. The performance improvement is primarily attributed to the gradual evaporation of organic butylammonium (BA+) spacer cations from the film as butylamine (BA) gas. This evaporation refines the film's composition and structure, leading to the spontaneous formation of larger-n phase RPPs, which exhibit superior carrier mobility. Consequently, the PCE of 2D-PSCs is enhanced. This work offers new insights into the structural evolution of 2D RPP films under ambient conditions and provides a feasible strategy for optimizing the performance of 2D-PSCs and other optoelectronic devices.

Construction of Linear Tetramer-Type Acceptors for High-Efficiency and High-Stability Organic Solar Cells.

Thanks to the development of non-fullerene acceptor (NFA) materials, the photovoltaic conversion efficiency (PCE) of organic solar cells (OSCs) has exceeded 20 %, which has met the requirements for commercialisation. In the current stage, the main focus is to balance the performance and stability. It has been shown that all-polymer formulation can improve device stability, however, PCE is not in satifsfaction, and the batch-to-batch variation leads to quality control issues. In this work, we constructed monodispersed tetramer NFA materials named G-1 and G-2, to best integrate the merits of small molecule and polymer. Density functional theory (DFT) calculations and experimental results showed that different connecting units at the centre could significantly affect the molecular planarity and thin film morphology. The alkene-bonded tetramer G-1 had a more regioregular structure, which leads to better molecular planarity, and more ordered packing in thin film. More importantly, the oligomeration induced a favourable face-on orientation, achieved a lower binding energy and exhibited a higher photoluminescence yield. As a result, the exciton and charge carrier kinetics was optimized with reduced non-radiative energy loss. The OSC based on PM6 : G-1 achieved a PCE of 19.6 %, which is the highest PCE reported so far for oligomer-based binary OSC. In addition, the device stability was largely improved, showing a lifetime over 10000 hours in the inverted OSC device.