Balanced Charge Carrier Transport Research Articles

Prolonging blue TADF-OLED lifetime through ytterbium doping of electron transport layer

Balanced charge carrier transport and broad carrier recombination zone are essential features for reducing triplet exciton concentration and suppressing triplet-mediated annihilation processes, which affect the performance and stability of blue-emitting organic light-emitting diodes (OLEDs) based on thermally activated delayed fluorescence (TADF) phenomenon. Doping of organic layers is among the most effective methods to control these features. Herein, the impact of ytterbium (Yb) doping of electron transport layer on the TADF-OLED performance, and particularly the lifetime, was thoroughly assessed. It was found that the lower doping concentrations of Yb (<10wt%) cause electron trapping and reduced current density, whereas higher Yb concentrations facilitate electron transport in the device. Although the introduction of Yb somewhat deteriorated device efficiency, it extended operational lifetime of blue-emitting device by 2 orders of magnitude (up to 46 hours at 1000 cd/m2). This was shown to occur as a result of Yb-assisted non-radiative triplet exciton quenching at the electron transport and emission layer interface, thus diminishing detrimental exciton annihilation processes.

Two compatible non-fullerene acceptors towards efficient ternary organic photovoltaics

The composition of organic active layers plays significant role in determining the photovoltaic performance of organic solar cells (OSCs). Ternary strategy has shown promising advantages in fabrication for highly efficient OSCs due to its simple process and various donor and acceptor materials. Herein, a famous small molecule acceptor (ITIC) was employed as an assistant acceptor to make efficient ternary organic solar cells (TOSCs). The use of ITIC shows good compatibility and leads to the formation of alloyed state with the host acceptor (BTP-eC9). The middle bandgap of ITIC is also complementary with those of the host active materials (BTP-eC9 and PM6), which will be beneficial for the light-harvesting and thus enhance the photocurrent for OSC devices. Furthermore, the introduction of ITIC can fine-tune the film morphology with continuous nanofiber interpenetrating network, which is great for more balanced charge carrier transport and efficiently suppressed charge recombination. Consequently, a prominent power-conversion-efficiency (PCE) was achieved up to 18.25% with all-around enhancement photovoltaic parameters for the PM6:BTP-eC9:ITIC-based TOSCs.

All-Solution-Processed Quantum Dot Light-Emitting Diode Using Phosphomolybdic Acid as Hole Injection Layer

In this study, we investigate phosphomolybdic acid (PMA), which allows solution processing of quantum dot light-emitting diodes. With its low cost, easy solution processes, and excellent physical and optical properties, PMA is a potential candidate as the hole injection layer (HIL) in optoelectronic devices. We evaluate the physical and electrical properties of PMA using various solvents. The surface morphology of the PMA film was improved using a solvent with appropriate boiling points, surface tension, and viscosity to form a smooth, pinhole-free film. The energy level was regulated according to the solvent, and PMA with the appropriate electronic structure provided balanced charge carrier transport in quantum dot electroluminescent (QD-EL) devices with enhanced efficiency. A device using PMA dissolved in cyclohexanone was demonstrated to exhibit improved efficiency compared to a device using PEDOT:PSS, which is a conventional solution HIL. However, the stability of PMA was slightly poorer than PEDOT:PSS; there needs to be further investigation.

Efficient All-Polymer Solar Cells with Sequentially Processed Active Layers.

In this work, we apply the sequential processing (SqP) method to address the relatively low electron mobility in recent all-polymer solar cells (all-PSCs) based on the polymerized small-molecule acceptor (PSMA). Compared to the blend-casting (BC) method, all-PSCs composed of PM6/PY-IT via the SqP method show boosted electron mobility and a more balanced charge carrier transport, which increases the FF of the SqP device and compensates for the short-circuit current loss, rendering comparable overall performance with the BC device. Through film-depth-dependent light absorption spectroscopy, we analyze the sub-layer absorption and exciton generation rate in the vertical direction of the device, and discuss the effect of the increased electron mobility on device performance, accordingly.

Multifunctional luminophores with dual emitting cores: TADF emitters with AIE properties for efficient solution- and evaporation-processed doped and non-doped OLEDs

• Three dual emitting core emitters are developed by coupling single core emitters. • The emitters possess high absorption coefficients and PLQY values in neat films. • Photophysical investigations demonstrate both AIE and TADF properties. • Highly efficient OLEDs with ultra-low efficiency roll-offs are achieved. Three novel emitters with dual emitting cores, namely 3,3′,5,5′-tetra(triphenylamine-4-yl)-[1,1′-biphenyl]-2,2′,6,6′-tetracarbonitrile (DDTPAIPN), 3,3′-di(triphenylamine-4-yl)-5,5′-di(3,5-(9,9′-dicarbazolyl)phenyl)-[1,1′-biphenyl]-2,2′,6,6′-tetracarbonitrile (DTPAmCPIPN), and 3,3′,5,5′-tetra(3,5-(9,9′-dicarbazolyl)phenyl)-[1,1′-biphenyl]-2,2′,6,6′-tetracarbonitrile (DDmCPIPN) are designed and synthesized by coupling their respective single core emitters. Compared with their single core counterparts, the three novel compounds exhibit significantly improved thermal stability, absorption coefficients, and photoluminescence efficiencies in neat films. Photophysical measurements show that these three emitters exhibit both aggregation-induced emission and thermally activated delayed fluorescence properties, which is beneficial for non-doped organic light-emitting diodes (OLEDs). The new compounds show relatively balanced charge carrier transport abilities as revealed by unipolar devices. The solution- and evaporation-processed doped and non-doped OLEDs made from these three luminophores achieve excellent electroluminescence (EL) performances. The peak current, power, and external quantum efficiencies of a DTPAmCPIPN-based solution-processed doped device reach 59.2 cd A −1 , 61.3 lm W −1 , and 17.2%, respectively, with an emission peak at 548 nm. The evaporation-processed doped device based on DTPAmCPIPN exhibits maximum EL efficiencies of up to 63.7 cd A −1 , 61.1 lm W −1 , and 19.2%. Moreover, the non-doped OLEDs also possess superior EL efficiencies with extremely small efficiency roll-offs. The molecular design strategy in this work is demonstrated to be effective in developing new emitters for efficient and stable OLEDs.

Publisher Correction: Design rules for high-efficiency both-sidescontacted silicon solar cells with balanced charge carrier transport and recombination losses

Publisher Correction: Design rules for high-efficiency both-sidescontacted silicon solar cells with balanced charge carrier transport and recombination losses

Systematic strategy for high-performance small molecular hybrid white OLED via blade coating at ambient condition

Large-area organic light-emitting diodes (OLEDs) fabricated by solution process with low-cost are essential for practical applications. However, maintaining desirable uniformity and smoothness of prepared films are challenging with the enhancement of film size and layers. Reported herein is a systematic strategy of solvent and device structure engineering for designing small molecular hybrid white OLED (WOLED) via blade-coating. Benefiting from the uniform blade-coated films with low roughness about 1 nm as well as the balanced charge carrier transport, the blade-coated WOLED with hybrid fluorescence and phosphorescence (small area 0.1 cm 2 ) shows the maximum current efficiency (CE), power efficiency (PE), and external quantum efficiency (EQE) of 29.0 cd A −1 , 30.4 lm W −1 , and 11.6%, respectively. And the WOLEDs achieve low turn-on voltage ( V on ) of about 2.8 V. Meanwhile, the all-vacuum-based WOLED reaches maximum CE, PE, and EQE of 40 cd A −1 , 44.3 lm W −1 , and 15.9%, respectively. Remarkably, a larger area of the device (2 cm × 2 cm) with uniform emitting reaches peak EQE of 6.8% by blade-coating, notably, only a small amount of solution about 0.9 μL/cm 2 was consumed for blade-coated films. The high-performance and low-cost WOLED via blade-coating is ascribed to the facile strategy to improve the film morphology and the energy-level matching, which provides huge potential in display and flat panel lighting. Benefiting from the solvent and device structure engineering, the blade-coated hybrid white organic light-emitting diodes (WOLEDs) reach external quantum efficiencies (EQEs) close to 12% (small-area, 0.1 cm 2 ) and 6.8% (2 cm × 2 cm) with a small amount of solution about 0.9 μL/cm 2 . • Fabricating a hybrid white organic light-emitting diodes (WOLEDs) by blade-coating at ambient conditions. • Selecting the ideal solvents (solvent engineering) and electron-transporting layer for the highly efficient blade-coating WOLED which reaches the maximum EQE, power efficiency (PE), and current efficiency (CE) of 11.6%, 30.4 lm W −1 , and 29.0 cd A −1 , respectively. • Fabricating a blade-coated WOLED (2 cm × 2 cm) owning peak EQE of 6.8% with a small amount of solution of 0.9 μL/cm 2 .

A wide-bandgap π-conjugated polymer for high-performance ternary organic solar cells with an efficiency of 17.40%

Although substantial progress has been made at increasing power conversion efficiencies (PCEs) the field of ternary organic solar cells (TOSCs) during the past few years, choice of π-conjugated polymers that exhibit strong complementary spectra and achieve high photovoltaic parameters (open-circuit voltage ( V oc), short-circuit current density ( J sc), fill factor (FF), and PCE) simultaneously is limited. In this paper, TOSCs demonstrated a high PCE of 17.09% based on a π-conjugated polymer (named SiCl-BDT, bandgap ≈ 1.84 eV) as a third component (15 wt%) to the host binary system consisting of a PM7:Y7. The third component was used to achieve enhanced absorption coefficient (λ max = 5.5 × 10 4 cm −1 ) and more balanced charge carrier transport, frontier molecular orbital (FMO) energy levels, and blend miscibility, contributed to an improved FF of 70.38% and yielded an impressive J sc of 27.37 mA/cm 2 and V oc of 0.84 V. The PCE was higher than the host PM7:Y7 (15.13%) binary device. In addition, we found the photovoltaic performance of TOSCs could be further increased to a benchmark PCE of 17.40% using an interface engineering strategy. Thus, enables efficient charge transfer in TOSCs compared with that of without interlayer TOSCs, leading to high J sc, V oc. The resulting encapsulation-free TOSCs showed excellent ambient and thermal stability. Accordingly, this work suggests that the use of a passivated electron transporting layer (ETL) and a π-conjugated polymer as a third component offers a promising means of overcoming the lower PCEs of OSCs. • The devices were fabricated in binary and ternary organic solar cells (TOSCs). • The cascade LUMO alignment and complementary absorption improve the performance of TOSCs. • The PCE of SiCl-BDT incorporated with binary host device (PM7:Y7) TOSCs reached to 15.12%, 17.09%. • An improved efficiency of 17.40% was achieved in a TOSC device using 3-(1-pyridinio)-1-propanesulfonate as a ZnO-passivation layer. • PM7:SiCl-BDT:Y7 based devices exhibit good thermal and ambient stability.

Balanced Charge Carrier Transport Mediated by Quantum Dot Film Post-organization for Light-Emitting Diode Applications.

In light-emitting diodes (LEDs), balanced electron and hole transport is of particular importance to achieve high rates of radiative recombination. Most quantum dot (QD)-based LEDs, however, employ infinitesimal core-shell QDs which inherently have different electron and hole mobilities. As QDs are the core building blocks of QD-LEDs, the inherent mobility difference in the core-shell QDs causes significantly unbalanced charge carrier transport, resulting in detrimental effects on performances of QD-LEDs. Herein, we introduce a post-chemical treatment to reconstruct the QD films through the solvent-mediated self-organization process. The treatment using various poly-alkyl alcohol groups enables QD ensembles to transform from disordered solid dispersion into an ordered superlattice and effectively modulate electron and hole mobilities, which leads to the balanced charge carrier transport. In particular, ethanol-treated QD films exhibit enhanced charge carrier lifetime and reduced hysteresis due to the balanced charge carrier transport, which is attributed to the preferential-facet-oriented QD post-organization. As a result, 63, 78, and 54% enhancements in the external quantum efficiency were observed in red, green, and blue QD-LEDs, respectively. These results are of fundamental importance to understand both solvent-mediated QD film reconstruction and the effect of balanced electron and hole transport in QD-LEDs.

Design rules for high-efficiency both-sides-contacted silicon solar cells with balanced charge carrier transport and recombination losses

The photovoltaic industry is dominated by crystalline silicon solar cells. Although interdigitated back-contact cells have yielded the highest efficiency, both-sides-contacted cells are the preferred choice in industrial production due to their lower complexity. Here we show that omitting the layers at the front side that provide lateral charge carrier transport is the key to excellent optoelectrical properties for both-sides-contacted cells. This results in a conversion efficiency of 26.0%. In contrast to standard industrial cells with a front side p–n junction, this cell exhibits the p–n junction at the back surface in the form of a full-area polycrystalline silicon-based passivating contact. A detailed power-loss analysis reveals that this cell balances electron and hole transport losses as well as transport and recombination losses in general. A systematic simulation study led to some fundamental design rules for future >26% efficiency silicon solar cells and demonstrates the potential and the superiority of these back-junction solar cells. Front- and back-junction silicon photovoltaics dominate the market thanks to a lower manufacturing complexity compared with that of other device designs yet advances in efficiency remain elusive. Richter et al. now present an optimized design for the front and back junctions that leads to a 26.0%-efficient cell.

Effect of alkyl side chain length on the electroluminescent performance of blue light-emitting poly(fluorene-co-dibenzothiophene-S,S-dioxide)

In this manuscript, we report a simple strategy of tuning the alkyl side chain length of emissive polymer to realize blue polymer light-emitting diodes (PLED) with high efficiency and enhanced device lifetime. Two poly(fluorene-co-dibenzothiophene-S,S-dioxide) derivatives, PF16SO and PF8SO, comprising the same backbone but different side chains lengths (hexadecyl only or hexadecyl mixed with octyl), were synthesized, respectively. Attributing to the stronger rigidity caused by its shorter side chains, PF8SO exhibits high glass-transition temperature of 218 °C and photoluminescence quantum yield of 78%. Furthermore, the grazing incidence X-ray diffraction measurements reveal closer π-π packing for PF8SO, resulting in improved and more balanced charge carrier transport. As a result, an enhanced electroluminescence performance with a low turn-on voltage of 2.8 V, a high luminous efficiency of 8.36 cd A−1 (corresponding to an external quantum efficiency of 6.19%) with the Commission Internationale de L’E'clairage coordinates of (0.15, 0.18) was achieved based on a single-layer device structure of ITO/PEDOT:PSS/Emissive Layer/Ba/Al, which is among the best performance reported so far for pure blue light-emitting polymers based on this simple device structure. In addition, PF8SO based device exhibits longer lifetime than that of PF16SO. The result indicates the great potential of tuning the alkyl side chain length in enhancement of electroluminescent performance for blue light-emitting poly (fluorene-co-dibenzothiophene-S,S-dioxide).

Magnetron sputtered all-metal-oxide layers with balanced charge carrier transport efficiency for long-term stable perovskite solar cells

Despite the great advance in power conversion efficiency (PCE), the poor stability of perovskite solar cells in ambient condition becomes a tremendous obstruction for real application. Solution-processed all-metal-oxide charge transport layers exhibit remarkable improvement in stability in ambient air according to the previous report. However, the solution process is confined to the limited effective area and morphology of the substrate. Here we report the magnetron sputtered charge transport layers, of which Cu doped NiOx (Cu:NiOx) acts as the hole transport layer and ZnO as the electron transport layer, respectively. We precisely control their properties on unlimited substrates without post-annealing for balanced charge transport efficiency in both interfaces, which demonstrates better power conversion efficiency. The all-metal-oxide based devices also demonstrate excellent stability in ambient condition when compared to the control devices based on conventional organic transport layers.

ZnO-Ti3 C2 MXene Electron Transport Layer for High External Quantum Efficiency Perovskite Nanocrystal Light-Emitting Diodes.

2D transition metal carbides, nitrides, and carbonitrides called MXenes show outstanding performance in many applications due to their superior physical and chemical properties. Herein, a ZnO–MXene mixture with different contents of Ti3C2 is applied as electron transport layers (ETLs) and the influence of the Ti3C2 MXene in all‐inorganic metal halide perovskite nanocrystal light‐emitting diodes (perovskite NC LEDs) is explored. The addition of Ti3C2 makes more balanced charge carrier transport in LEDs by changing the energy level structure and electron mobility of ETL. Moreover, lower surface roughness is obtained for the ETL, thus guaranteeing uniform distribution of the perovskite NCs layer and further reducing leakage current. As a result, a 17.4% external quantum efficiency (EQE) with low efficiency roll‐off is achieved with 10% Ti3C2, which is a 22.5% improvement compared to LEDs without Ti3C2.

Unveiling Photovoltaic Performance Enhancement Mechanism of Polymer Solar Cells via Synergistic Effect of Binary Solvent Additives

Binary solvent additive engineering is an effective strategy to optimize photoactive films for high‐efficiency organic solar cells, however, the effect of single components on device performance and the combination principle of binary solvent additives remain unclear. Herein, synchrotron‐based grazing incident X‐ray diffraction, Derjaguin–Muller–Toporov modulus imaging, and plasmon energy shift imaging acquired by scanning transmission electron microscopy to investigate the effect of new binary solvent additive of 1,8‐diiodooctane (DIO) and less‐toxic and p‐anisaldehyde (AA) on device performance of solar cells based on poly[(5,6‐difluoro‐2,1,3‐benzothiadiazol‐4,7‐diyl)‐alt‐(3,3‴‐di(2‐octyldodecyl)2,2′;5′,2″;5″,2‴‐quaterthio‐phen‐5,5‴‐diyl)] (PffBT4T‐2OD) and [6,6]‐phenyl‐C61‐butyric acid methyl ester (PC61BM) are used. It is found that AA mainly favors polymer order and high crystallinity of PffBT4T‐2OD. Differently, DIO mainly enables PC61BM diffusing into PffBT4T‐2OD polymer matrix, leading to enlarged donor–acceptor (D–A) interface. As expected, by combining AA and DIO, the composite film provides large D–A interface and more balanced charge carrier transport. Consequently, their beneficial synergistic effect results in enhanced short circuit current and fill factor, and thereby increased power conversion efficiency of 10.64%, improved by 16% with respect to the control device. Herein, a general mechanism of enhancing device performance via the combination of solvent additives with different contributions to photoactive film is unveiled.

Improving performance of perovskite solar cells based on ZnO nanorods via rod-length control and sulfidation treatment

The structure and properties of electron transport layers play an important role in determining device performance of perovskite solar cells (PSCs). PSCs based on one-dimensional ZnO nanorods still suffer from serious efficiency losses. In this work, length of ZnO nanorods was firstly optimized by exploring steady photoluminescence quenching of perovskite films deposited on ZnO nanorods of various lengths and their photovoltaic performance. PSCs fabricated on ZnO nanorods of ~400 nm yield the best power conversion efficiency of ~10% due to their relatively balanced charge carrier transfer and transport properties. On this basis, sulfidation treatment was applied on these ZnO nanorods to further improve device performance. It is found that the sulfidation treatment of ZnO nanorods may play a role in at least three aspects: (I) passivating defects on the surface of ZnO nanorods; (II) facilitating charge carrier transfer and transport by forming ZnO/ZnS type II heterojunctions; (III) alleviating perovskite dissociation to some extent. Due to these benefits, the power conversion efficiency of perovskite solar cells based on ZnO nanorods was improved to 11.72%, along with less hysteresis. This work not only demonstrates the importance of rod-length and sulfidation treatment on device performance of perovskite solar cells based on ZnO nanorods but also provides a feasible method to improve their power conversion efficiency.

Asymmetrically Alkyl‐Substituted Wide‐Bandgap Nonfullerene Acceptor for Organic Solar Cells

An asymmetric wide‐bandgap (WBG) nonfullerene acceptor (C6‐IDTT‐T) is developed by shearing one alkyl side‐chain from a symmetrically alkyl‐substituted indacenodithieno[3,2‐b]thiophene (IDTT) core of the fused‐ring electron acceptor 2C6‐IDTT‐T. These two acceptors both exhibit wide optical bandgaps over 1.8 eV. Investigations on the optical, electrochemical, and active layer morphology are conducted to understand the effect of asymmetric side chains on the electrical and photovoltaic properties. Compared with symmetric 2C6‐IDTT‐T, asymmetric C6‐IDTT‐T is found to exhibit redshifted absorption and higher electron mobility. As a result, the C6‐IDTT‐T blend with a thienothiophene‐benzodithiophene copolymer (PTB7‐Th) presents higher electron mobility and more balanced charge carrier transport, which leads to an enhanced power conversion efficiency of 8.51% for C6‐IDTT‐T‐based device with a high open‐circuit voltage of 1.052 V and a low energy loss of 0.60 eV.

Low turn-on voltage of doped organic light emitting diodes based on food dyes

Three derivatives of food azo dye were investigated (Dyes 1, 2 and 4) by theoretical and experimental tools. Photophysical properties, based on theoretical estimations, experimental evaluations, electrochemical and photoelectrical properties were discussed. The compounds exhibited efficient emission of solid state with maximum fluorescence intensity at the range of 517–646 nm and PLQY (photoluminescence quantum yield) values at the range of 9–17% in non-doped solid state and 13–39% in doped solid state. In this study 90 wt percent of PBD (2-(4-tert-Butylphenyl)-5-(4-biphenylyl)-1,3,4-oxadiazole) have been used as the electron transporting host who derived balanced charge carrier transport for high internal and external efficiency of OLEDs (organic light emitting diodes). Ionization potential for compounds was found to be comparable (5.85 and 6.18 eV) by photoelectron emission spectrometry. According to the fabrication of devices for gaining charge mobility the layers of the dyes showed properties as a bipolar charge transporting with balanced hole and electron mobility and the values reaching to 1.27 × 10−4 cm2/Vs and 1.09 × 10−4 cm2/Vs respectively at high electric fields. Furthermore, OLEDs consist of azo dyes as an emitter layer fabricated by PVD (physical evaporation deposition) method and the maximum values of the best device showed, consist of, the low turn on voltage of 2.69 V and values of brightness, current efficiency, power efficiency, EQE (external quantum efficiency) 16432.40 cd/m2, 8.20 cd/A, 6.95 lm/w, 4.89% respectively.

Highly Efficient Blue Electroluminescent Materials Based on Phenanthro[9,10-d] imidazole

Phenanthro[9,10-d]-imidazole( PI) unit has attracted extensive attentions in organic optoelectronic field due to its intrinsic wide band gap,high luminescence efficiency,good thermal stability,balanced charge carrier injection and transport property as well as low fabrication cost. In this manuscript,the recently reported blue electroluminescent PI derivatives were reviewed. The structure characteristics of PI were demonstrated,and the structure-property relationships of some PI derivatives were summarized systemically. At last,all the reported highly efficient nondoped deep blue emitters were summed up in order to comprehensively evaluate the potentials of PI derivatives in organic light emitting diodes( OLEDs) in the future.

Star-Shaped Magnesium Tetraethynylporphyrin Bearing Four Peripheral Electron-Accepting Functionalities for Organic Solar Cell

Magnesium tetraethynylporphyrins bearing four electron-deficient diketopyrrolopyrrole (DPP; Mg-TEP-DPP4) units were synthesized by Sonogashira coupling, andtheir optical and electrochemical properties were investigated. The energy levels were effectively tuned by DPP with or without electron-withdrawing end-caps. Importantly, all the Mg-TEP-DPP4moleculeshave broad absorption bands across the visible and near-infrared regions. The time-dependent excited state features of Mg-TEP-DPP4molecules and their kinetics wereinvestigatedby femtosecond transient absorption spectroscopy in combination with multiwavelength and global/target analyses of time-resolved spectra. Importantly, the charge-separated state was demonstrated to undergo recombination within 253 ps in benzonitrile. Bulk heterojunction organic solar cells fabricated with Mg-TEP-DPP4:PC61BM exhibited a power conversion efficiencyof 7.40% after solvent vapor annealing, which enabled balanced charge carrier transport, reduced charge recombination, and favorable charge separation and collection.

Charge carrier transport and nanomorphology control for efficient non-fullerene organic solar cells

Single junction organic photovoltaic devices (OPVs) have exceeded 15% power conversion efficiency (PCE) with the help of fused ring based low-bandgap non-fullerene acceptors (NFAs). As a major type of NFA, the indacenodithiophene derivative NFA (IDTBR) has been shown to have superior OPV stability with outstanding VOC, but the efficiency is relatively lower compared to the reported OPV champion devices. Further improvements towards high efficiencies in this OPV system remains challenging due to the relatively poor charge carrier transport properties in the bulk heterojunction film, particularly the electron transport in small molecule non-fullerene acceptor network. Here we conducted detailed study on the dependence of carrier transport on BHJ donor–acceptor (D–A) composition. Our results show that the nano-morphology or phase aggregation of non-fullerene acceptor (NFA) molecules can be tuned via D–A composition in bulk heterojunction layer, and the improvement of electron mobility was shown to be enhanced by almost one order – from 1.23 × 10−6 cm2/V (D:A = 1:1 by weight) to 1.02 × 10−5 cm2/V (D:A = 1:2) – due to the improved connectivity of electron transport pathways. Further increase of NFA component content, however, has led to over-sized phase segregation, deteriorating the photovoltaic performance of organic soar cells. The optimized BHJ cell shows more balanced charge carrier transport and phase segregation, which yields a PCE of 10.79%. Furthermore, it shows a VOC as high as 1.03 V, which is ascribed to the significantly suppressed radiative and non-radiative recombination losses with bandgap-VOC offset Eg/q-VOC of only 0.55 V.