Improvement In Device Efficiency Research Articles

Phenylethylammonium iodide induced “in situ healing” behavior for carbon-electrode basing, hole-conductor-free perovskite solar cells

Previous study showed that blending octylammonium iodide (OAI) in a carbon paste induced a kind of in situ healing effect for carbon-electrode basing, hole-conductor-free, planar perovskite solar cells. Here, the strategy is re-examined by considering another kind of ammonium halide molecule or phenethylammonium iodide (PEAI). It is observed that, after moderate PEAI blending, power conversion efficiency of devices rises from 11.56 (±0.82)% to 15.77 (±0.53)% (championed at ∼17.9%), with open-circuit voltage increasing from 969 (±28) to 1033 (±13) mV, and fill factor increasing from 51.17 (±2.68)% to 65.71 (±1.36)%. The improved device efficiency is due to the retarded charge recombination and the improved charge transfer processes. Transient photovoltage/photocurrent decay curve tests show that, after PEAI blending, lifetime of charge carriers in device increases from 3.21 to 5.67 μs, while the charge extraction time decreases from 2.99 to 2.18 μs. Moreover, built-in potential rises according to the Mott–Schottky study. A designated “penetration-reaction” test reveals that PEAI could also induce the in situ healing effect, which accounts for the improved charge transfer/recombination processes. The study could tell the universality of this strategy to certain extent.

Impact of Buried Interface Texture on Compositional Stratification and Ion Migration in Perovskite Solar Cells

AbstractDespite the striking increase in the power conversion efficiency (PCE) of lead‐based perovskite solar cells (PSCs), their poor operational stability impedes their commercialization. Among the various factors that influence device stability, ion migration has been identified as a key driver of degradation. In this work, the focus is on studying ion migration‐induced degradation in inverted architecture PSCs, which employ either a thin polymer layer or a self‐assembled monolayer (SAM) for hole extraction. It is demonstrated that the difference in texture imposed by the use of these hole transport layers (HTL) is an important and thus far inconspicuous factor that impacts ion migration, and consequently device stability. By investigating the buried interface in detail, it is revealed that its texture has a strong impact on the vertical compositional stratification in the perovskite active layer. By monitoring bias‐induced ion migration in devices with different hole extraction layers, it is demonstrated that the smooth polymer‐based HTL results in a higher degree of ion migration than the rough SAM HTL, corresponding to a stronger degradation in the former. These results further indicate that the use of SAMs for hole extraction is a promising strategy to suppress ion migration and improve device efficiency.

Transfer of 2D Films: From Imperfection to Perfection.

Atomically thin 2D films and their van der Waals heterostructures have demonstrated immense potential for breakthroughs and innovations in science and technology. Integrating 2D films into electronics and optoelectronics devices and their applications in electronics and optoelectronics can lead to improve device efficiencies and tunability. Consequently, there has been steady progress in large-area 2D films for both front- and back-end technologies, with a keen interest in optimizing different growth and synthetic techniques. Parallelly, a significant amount of attention has been directed toward efficient transfer techniques of 2D films on different substrates. Current methods for synthesizing 2D films often involve high-temperature synthesis, precursors, and growth stimulants with highly chemical reactivity. This limitation hinders the widespread applications of 2D films. As a result, reports concerning transfer strategies of 2D films from bare substrates to target substrates have proliferated, showcasing varying degrees of cleanliness, surface damage, and material uniformity. This review aims to evaluate, discuss, and provide an overview of the most advanced transfer methods to date, encompassing wet, dry, and quasi-dry transfer methods. The processes, mechanisms, and pros and cons of each transfer method are critically summarized. Furthermore, we discuss the feasibility of these 2D film transfer methods, concerning their applications in devices and various technology platforms.

Etching-free pixel definition in InGaN green micro-LEDs

The traditional plasma etching process for defining micro-LED pixels could lead to significant sidewall damage. Defects near sidewall regions act as non-radiative recombination centers and paths for current leakage, significantly deteriorating device performance. In this study, we demonstrated a novel selective thermal oxidation (STO) method that allowed pixel definition without undergoing plasma damage and subsequent dielectric passivation. Thermal annealing in ambient air oxidized and reshaped the LED structure, such as p-layers and InGaN/GaN multiple quantum wells. Simultaneously, the pixel areas beneath the pre-deposited SiO2 layer were selectively and effectively protected. It was demonstrated that prolonged thermal annealing time enhanced the insulating properties of the oxide, significantly reducing LED leakage current. Furthermore, applying a thicker SiO2 protective layer minimized device resistance and boosted device efficiency effectively. Utilizing the STO method, InGaN green micro-LED arrays with 50-, 30-, and 10-µm pixel sizes were manufactured and characterized. The results indicated that after 4 h of air annealing and with a 3.5-μm SiO2 protective layer, the 10-µm pixel array exhibited leakage currents density 1.2 × 10−6 A/cm2 at −10 V voltage and a peak on-wafer external quantum efficiency of ~6.48%. This work suggests that the STO method could become an effective approach for future micro-LED manufacturing to mitigate adverse LED efficiency size effects due to the plasma etching and improve device efficiency. Micro-LEDs fabricated through the STO method can be applied to micro-displays, visible light communication, and optical interconnect-based memories. Almost planar pixel geometry will provide more possibilities for the monolithic integration of driving circuits with micro-LEDs. Moreover, the STO method is not limited to micro-LED fabrication and can be extended to design other III-nitride devices, such as photodetectors, laser diodes, high-electron-mobility transistors, and Schottky barrier diodes.

Impact of blocking layers based on TiO2 and ZnO prepared via direct current reactive magnetron sputtering on DSSC solar cells

The optimization of dye-sensitized solar cells (DSSCs) technology towards suppressing charge recombination between the contact and the electron transport layer is a key factor in achieving high conversion efficiency and the successful commercialization of this type of product. An important aspect of the DSSC structure is the front blocking layer (BL): optimizing this component may increase the efficiency of photoelectron transfer from the dye to the semiconductor by reduction charge recombination at the TiO2/electrolyte and FTO/electrolyte interfaces. In this paper, a series of blocking layer variants, based on TiO2 and ZnO:TiO2, were obtained using the reactive magnetron sputtering method. Material composition, structure and layer thickness were referred to each process parameters. Complete DSSCs with structure FTO/BL/m-TiO2@N719/ EL-HSE/Pt/FTO were obtained on such bases. In the final results, verification of opto-electrical parameters of these cells were tested and used for the conclusions on the optimal blocking layer composition. As the conclusion, application of blocking layer consists of neat TiO2 resulted in improvement of device efficiency. It should be noted that for TiO2:ZnO/CuxO and TiO2/CuxO cells, higher efficiencies were also achieved when pure TiO2 was used as window layer. Additionally it was proven that the admixture of ZnO phase inspires Voc and FF growth, but is overall unfavorable compared to pristine TiO2 blocking layer and the reference cell, according to the final cell efficiency.

Hydrogen‐Bonding Interactions Between Terpolymers Enable Excellent Device Efficiency and Operational Stability of Non‐Halogenated Solvent‐Processed Polymer Solar Cells

AbstractAlthough polymer solar cells (PSCs) have shown considerable power conversion efficiency (PCE) potential, their poor operational stability is a major obstacle for their future commercialization. In this study, the ternary‐blend strategy based on D1–A–D1–D2‐type conjugated random terpolymers containing hydrogen–bonding sites is employed to simultaneously improve device efficiency and long‐term stability. Notably, the PM6‐ThEG:PM6‐ThOH:Y6‐BO ternary‐blend system exhibits a remarkable PCE of 17.2% with superior photo, thermal, and mechanical stability, outperforming those of binary devices based on PM6, PM6‐ThEG, and PM6‐ThOH polymer donors. These outstanding results are likely attributed to the robust molecular lock via hydrogen bonds between PM6‐ThEG and PM6‐ThOH terpolymers, which can induce strong intermolecular packing, a dense 3D terpolymer network, and optimized morphology. These results also correlate well with the computational study. A comprehensive analysis of optoelectronic and morphological properties as well as the exploration of underlying physical mechanisms collectively verifies the effectiveness of this approach based on mixed random terpolymers with hydrogen‐bonding moiety to achieve the non‐halogenated solvent‐processed PSCs with exceptional efficiency and operational stability.

Critical role of the end-group acceptor in enhancing the efficiency of indacenodithiophene-benzothiadiazole-linked nonfullerene organic solar cells through morphology optimization

Solution-processed organic solar cells (OSCs) have great promise for next-generation solar energy conversion technologies. Innovative acceptors are constantly being designed to improve device efficiency. In this work, we designed and synthesized a series of A–π–D–π–A type non-fullerene acceptor (NFA) molecules, named IB-TOT, IB-TOM, IB-IOO, and IB-IOM for their applications in OSCs. All molecules showed high thermal stability, broad photoabsorption, and relatively lower highest occupied molecular orbital (HOMO) energy levels from −5.48 eV to −5.58 eV. The optimized OSCs based on these NFAs and PTB7-Th donor deliver power conversion efficiencies (PCEs) of 8.19%, 5.50%, 2.42%, and 3.10% for IB-TOT, IB-TOM, IB-IOO, and IB-IOM molecules, respectively. The higher PCE of IB-TOT-based OSCs is attributed to their excellent miscibility and superior interpenetrating network morphology compared to the other three compounds. These results demonstrate that using the 3-ethylrhodanine acceptor unit to construct the NFA molecule is a successful approach for outstanding achievement in OSCs.

Fluorine substitutions engineering of benzotriazole‐based hole transport polymers toward high‐performance CsPbI2Br perovskite solar cells

AbstractDeveloping suitable hole transport materials is of utmost importance in the quest to enhance the performance of CsPbI2Br perovskite solar cells (PSCs). Among the various undoped hole transport materials (HTMs), D‐π‐A type polymers incorporating benzodithiophene (BDT) as the D unit and benzotriazole (BTA) as the A unit have shown promising potential. To further optimize the energy level and enhance the hole transport ability of these HTMs, we employed a fluorine substitution strategy to synthesize P‐BTA‐2F and P‐BTA‐4F based on the polymer P‐BTA‐0F. Subsequently, we investigated the impact of varying degrees of fluorine substitution on the properties of the polymer materials and the performance of the devices. As the number of F substitutions increases, the polymer energy level of the HTM gradually shifts downward, the face‐on stacking of the HTM strengthens, the hole mobility of the HTM increases, and the rate of hole extraction and transport becomes faster. Ultimately, the CsPbI2Br PSCs based on the P‐BTA‐4F HTM achieve the highest power conversion efficiency (PCE) of 17.68%. Those findings demonstrate that selecting an appropriate amount of fluorine substitution is crucial for regulating the performance of polymer HTMs and improving device efficiency.

Enhancing Efficiency in Inverted Quantum Dot Light-Emitting Diodes through Arginine-Modified ZnO Nanoparticle Electron Injection Layer

Many quantum dot light-emitting diodes (QLEDs) utilize ZnO nanoparticles (NPs) as an electron injection layer (EIL). However, the use of the ZnO NP EIL material often results in a charge imbalance within the quantum dot (QD) emitting layer (EML) and exciton quenching at the interface of the QD EML and ZnO NP EIL. To overcome these challenges, we introduced an arginine (Arg) interlayer (IL) onto the ZnO NP EIL. The Arg IL elevated the work function of ZnO NPs, thereby suppressing electron injection into the QD, leading to an improved charge balance within the QDs. Additionally, the inherent insulating nature of the Arg IL prevented direct contact between QDs and ZnO NPs, reducing exciton quenching and consequently improving device efficiency. An inverted QLED (IQLED) utilizing a 20 nm-thick Arg IL on the ZnO NP EIL exhibited a 2.22-fold increase in current efficiency and a 2.28-fold increase in external quantum efficiency (EQE) compared to an IQLED without an IL. Likewise, the IQLED with a 20 nm-thick Arg IL on the ZnO NP EIL demonstrated a 1.34-fold improvement in current efficiency and a 1.36-fold increase in EQE compared to the IQLED with a 5 nm-thick polyethylenimine IL on ZnO NPs.

Cyanoesterthiophene Based Low‐Cost Polymer Donors for High Efficiency Organic Solar Cells

AbstractTo achieve commercial application of organic solar cells (OSCs), it is necessary to reduce material costs and improve device efficiency. This paper reports on the utilization of a multifunctional building block, namely 3‐cyanoesterthiophene, which exhibits simple structure and accessibility of synthetic for cost‐effective and high‐performance polymer donors (PDs). Meanwhile, ternary and terpolymerization strategies have been studied. Two similar PDs, PBTCl0‐TCA and PBTCl100‐TCA, are synthesized, and the devices exhibit less‐than‐satisfactory efficiency of 13.21% and 11.53% due to mismatching energy level and imperfect morphology. The two PDs with comparable structures and commendable compatibility easily form alloy‐like phase in active layer, which can effectively boost the efficiency of ternary devices to 14.17% with retained high JSC and significant improved open‐circuit voltage (VOC) and fill factor (FF). Encouraged by the ternary blending phenomenon, a polymer donor (PBTCl50‐TCA) with same ratio by random terpolymerization is designed. And over 17% efficiency binary OSCs using terpolymerization donor are demonstrated. The synergies of incorporation of the cyanoester‐group and terpolymer endow the developed PDs with deep‐lying energy levels, face‐on orientation, thermodynamic miscibility with the prevailing nonfullerene acceptor and appropriate polymer crystallinity. The findings study provide valuable insights and support for the advancement of cost‐effective and high‐performance PDs.

Efficient quasi-2D tin perovskite solar cells based on mixed monoammonium and diammonium terminal molecules

The use of a diammonium ligand, p-Xylylenediammonium thiocyanate, enhances the carrier transfer and improves device efficiency.

Harvesting of Atmospheric Water Using Polymer‐Based Hybrid Hydrogels

AbstractAtmospheric water harvesting (AWH) is an important parallel or supplemental freshwater production technique to liquid water resource‐based technologies due to the availability of moisture resources regardless of location and the possibility of realizing decentralized applications. Recent developments to regulate the characteristic features and nanostructures of moisture‐harvesting materials demonstrate new opportunities to improve device efficiency. Focusing on the design of water harvesting materials and the optimization of the overall system, this review sums up the most recent developments in this area and presents prospects for the future development of AWH. An overview of the processes involved in water sorption by various sorbents and the characteristics and functionality of the polyaniline‐based hydrogels developed for AWH is given. Newly reported hydrogel sorbents used for AWH are evaluated, focusing on their benefits, drawbacks, and design methodologies. Several AWH‐specific water harvesters are described and the impact of the system's mass and heat transfer on its operational effectiveness is explored. Finally, potential roadmaps for the development of this technology are detailed and the challenges in this subject from both a basic research and practical application perspective are discussed.

Interface Engineering for Highly Efficient Perovskite Photovoltaics

In the past decade, major progress has taken place in the field of metal halide perovskite photovoltaics (PV), as witnessed by the recently achieved conversion efficiency of 25.7% [1] and the concrete opportunity to go beyond the thermodynamic limit of single junction PV by means of perovskite/ crystalline silicon tandems, with the very recent record of 33.2% [2]. Among the most recent efforts towards further development of perovskite PV and subsequent commercialization, strategies ranging from perovskite surface passivation and compositional engineering to thin film encapsulation, contribute to suppress the perovskite absorber and device instability to moisture ingress. In parallel, research efforts presently investigate the role of inorganic charge transport layers (CTLs) next to the one of the most commonly used organic CTLs, such as poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine (PTAA), [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) or C60. The inorganic layers are acknowledged to impart thermal and mechanical stability to the device, as well as to improve device efficiency yield.In this contribution, our recent research on atomic layer deposited (ALD) selective CTLs for metal halide perovskite PV [3] is reviewed by addressing two case studies, namely, SnO2 thin films, selective towards electron transport, and NiO thin films, selective towards hole transport. ALD is selected as deposition technology because of its merit of ultimate control over film thickness and conformality.ALD SnO2 [4]. based on cycles of tetrakis(dimethylamido)-tin and H2O as precursor and co-reactant, respectively, is the state-of-the art in both p-i-n perovskite single junction as well as tandem perovskite/crystalline silicon and perovskite/CIGS PV. Its presence is key to the device thermal and mechanical stability, to prevent humidity ingress in the device and suppress damage to the fullerene (PCBM or C60) during the sputtering of the transparent front contact. Moreover, SnO2 plays a key role in perovskite/perovskite tandem PV, where it serves as solvent barrier to prevent damage of the wide-band gap perovskite sub-cell during solution processing of the narrow-band gap perovskite top cell. In parallel, our in situ studies by means of IR spectroscopy during ALD of SnO2 on perovskite/fullerene disclose the reason behind the difference in device conversion efficiency when SnO2 is processed either on PCBM or C60, i.e. the devices based on PCBM underperform those based on C60 by 3% absolute difference. Specifically, the Sn-precursor is responsible for the modification of the ester group in PCBM thereby affecting the PCBM/perovskite interface and device efficiency.ALD NiO thin (7 nm) films [5], based on cycles of bis(methylcyclopentadienyl)nickel and H2O as precursor and co-reactant, respectively, are found to impart stability to the perovskite device under acceleration test at 85°C, with 80% retention of the initial conversion efficiency after 300 hours at 1 sun illumination. At the same time, the presence of the phosphonic acid-based self-assembled monolayer (SAM), is essential to engineer an almost lossless (i.e., in terms of suppression of charge recombination) NiO/SAM/perovskite interface. Also, the SAM homogeneity and surface coverage on NiO improve with respect to direct SAM processing on ITO (see figure), as witnessed by transmission electron microscopy (TEM) and conductive atomic force microscopy. This result is explained in terms of chemisorption reactions between SAM phosphonic acid groups and NiO hydroxyl groups. The SAM homogeneity on NiO leads to higher shunt resistance in the device with respect to the one with SAM directly processed on ITO. Finally, the combination of NiO and SAM results in a narrower distribution of device performance reaching more than 20% efficient champion device. In parallel, two-terminal perovskite/crystalline silicon tandem devices with an ITO/NiO/SAM tunnel recombination junction (TRJ) exhibit a better device yield with respect to tandem devices with an ITO/SAM TRJ, i.e. the standard deviation decreases from 4.6% with ITO/SAM to 2.0% with ITO/NiO/SAM.[1] Green et al., Prog. Photovolt. Res. Appl. 30, 687 (2022)[2] https://www.kaust.edu.sa/news/kaust-team-sets-world-record-for-tandem-solar-cell-efficiency[3] Zardetto et al., Sustainable Energy & Fuels 1, 30 (2017)[4] Bracesco et al., J. Vac. Sci. Technol. A, 38(6), 063206-1 (2020)[5] Phung et al., ACS Applied Materials and Interfaces. 14(1), 2166 (2022)[6] Phung et al., submitted to Sol. Mat. (2023) Figure 1

Efficient D1:D2:A ternary all-polymer solar cell with optimized photoactive layer morphology realized by compatible two polymer donor

All-polymer solar cells (all-PSCs) have excellent morphology stability, but the efficiency is low related to that based on small molecule, due to the difficulty of morphology regulation in all-PSCs. Herein, the polymer donor D18-Cl is selected as third component and incorporated into host binary system PM6:PY-IT, then study the effect of the third component on regulating photoactive layer and improving device efficiency. The related experimental result demonstrates that the efficiency is improved obviously with the addition of D18-Cl. Through systematic characterization and analysis, we find that the third component D18-Cl have complementary absorption spectra with host binary system, which broaden the range of absorption spectra. In addition, photoactive layer morphology is optimized well with the incorporation of the third component, which is beneficial for exciton separation and carrier transfer and can also suppress charge recombination loss in devices. As results, compared with 15.08 % of control group, the efficiency of optimized ternary all-polymer solar cell is improved to 16.01 %. Therefore, this work demonstrates that optimized photoactive layer morphology and improved efficiency can be achieved by choosing suitable third component.

Efficient methylammonium lead triiodide CH3NH3PbI3 perovskite solar cells with improved surface properties using PM6 (PBDB-T-2F) polymer

Polymer additives are extensively used and serve a crucial role in the advancement of CH3NH3PbI3 perovskite photovoltages. This work demonstrates the effect of Poly[(2,6-(4,8-bis(5-(2-ethylhexyl-3-fluoro)thiophen-2-yl)-benzo[1,2-b:4,5-b’]dithiophene))-alt-(5,5-(1′,3′-di-2-thienyl-5′,7′-bis(2-ethylhexyl)benzo[1′,2′-c:4′,5′-c’]dithiophene-4,8-dione)PBDB-T-2F (PM6) at various concentrations on the crystallinity, surface structure, optical and electrical properties of CH3NH3PbI3 perovskite thin films. Polymer molecules are utilized to promote the growth of crystal particles in the active layer. The chemical reaction between their functional groups and theperovskite absorber and transportation layers leads to defect passivation and improved device efficiency. The results show that the absorption spectra of CH3NH3PbI3:PM6 perovskite thin films cover the extensive absorption spectra in the UV and visible light range between 500 and 800 nm, indicating that CH3NH3PbI3:PM6 perovskite is an effective visible light absorber. The PL intensity decreased as the polymer PM6 concentration increased up to 6 mg/ml, then increased when the concentration of PM6 was raised to 8 mg/ml. Quenching the sample with 6 mg/mL of PM6 caused rapid electron transfer to the substrate. According to surface morphology findings, the perovskite film's irregularity was reduced from 37.05 nm for pure thin film to 12.27 nm when added 6 mg/ml of PM6. The 6 mg/mL PM6 film exhibited the most uniformity and fluidity. The surface of the perovskite film was transformed into smooth, compacted pores with a particle size of 2 µm, which could facilitate charge transport for enhanced photovoltaic performance. The solar cell devices had a PCE of 14.68 %, a short-circuit current density of 19.32 mA/cm2, an open circuit voltage of 1.20 V, and a fill factor of 63.35 %.

In Situ Dual-Interface Passivation Strategy Enables The Efficiency of Formamidinium Perovskite Solar Cells Over 25.

Perovskite solar cells (PSCs) are promising candidates for next-generation photovoltaics owing to their unparalleled power conversion efficiencies (PCEs). Currently, approaches to further improve device efficiencies tend to focus on the passivation of interfacial defects. Although various strategies have been developed to mitigate these defects, many involve complex and time-consuming post-treatment processes, thereby hindering their widespread adoption in commercial applications. In this work, a concise but efficient in situ dual-interface passivation strategy is developed wherein 1-butyl-3-methylimidazolium methanesulfonate (MS) is employed as a precursor additive. During perovskite crystallization, MS can either be enriched downward through precipitation with SnO2 , or can be aggregated upward through lattice extrusion. These self-assembled MS species play a significant role in passivating the defect interfaces, thereby reducing nonradiative recombination losses, and promoting more efficient charge extraction. As a result, a PCE >25% (certified PCE of 24.84%) is achieved with substantially improved long-term storage and photothermal stabilities. This strategy provides valuable insights into interfacial passivation and holds promise for the industrialization of PSCs.

Diffusible Capping Layer Enabled Homogeneous Crystallization and Component Distribution of Hybrid Sequential Deposited Perovskite.

Nowadays, the development of wide-bandgap perovskite by thermal evaporation and spin-coating hybrid sequential deposition (HSD) method has special meaning on textured perovskite/silicon tandem solar cells. However, the common issues of insufficient reaction caused by blocking of perovskite capping layer are exacerbated in HSD, because evaporated precursors are usually denser with higher crystallinity and the widely used additive-assisted microstructure is also difficult to access. Here, a facile "diffusible perovskite capping layer" (DPCL) strategy to solve this dilemma is presented. With DPCL, crystallization alleviation of perovskite and more diffusion channels of organic salts can be realized simultaneously, contributing to a homogenization process. The resultant perovskite films exhibit complete conversion, uniform crystallization, enhanced quality, and reduced defect, leading to obvious improvements in device efficiency, repeatability, and stability. This work offers a way to promote the development of textured tandems a step further.

Manipulating the Charge Carriers Through Functionally Bridged Components Advances Low‐Cost Organic Solar Cells with Green Solvent Processing

AbstractOrganic solar cell (OSC) development continues to demonstrate impressive device efficiency improvements. However, the materials synthetic simplicity essential to industrialization remains seriously lacking attention, imparting inferior performance records in low‐cost devices. Hence, low bandgap and completely non‐fused electron acceptors (CNFEAs) having simple molecular structures are investigated herein. In contrast to typically explored fused‐ring acceptors with smaller backbone conformational variations, minimizing the interface recombination sites through a greater extent of localized domains is identified as more critical in CNFEAs, leading to remarkable fill factors (FFs) approaching 75%, among the highest currently realized for low‐cost systems. However, this comes with diminishing charge generation efficiency. The general ternary blend optimization strategy modifying the morphology of host components is limited in preserving such remarkably high FFs. To suppress the trade‐off while keeping notable FFs, a new perspective of constructing functionally bridged components based on optical, electronic, and thermodynamic properties is introduced here. Specifically, charge generation is unrestrained from the host acceptor localized domains through the introduction of a “bridge” component while also taking advantage of the configuration to channel polarons toward the efficient transport moieties of the host components. Accordingly, this work incubates understanding‐guided optimizations toward the advancement of more practical devices.

Simultaneous inclusion of quantum dots in multi-functional layers of thin film organic solar cells

The role of quantum dot (QD) decoration in the hole transport buffer layer and the photoactive medium on the photovoltaic parameters of thin film organic solar cells (TFOSCs) was investigated. A cadmium–tellurium-based QD was synthesized successfully and embedded in two of the functional layers of a TFOSC to improve its overall power conversion efficiency. The experimentally determined optimum concentration of the QD was maintained in the interfacial layer to investigate the effect of QD concentration in the active layer. The observed increased short-circuit current density (Jsc) and open circuit voltage (Voc) are attributable to the enhanced energy level tuning, broadened optical absorption, and charge transport process facilitated by the integration of QDs inside the media. Moreover, an improved device efficiency was obtained when the solvent additive was introduced into the bulk heterojunction photoactive layer films to facilitate QD dispersion and increase the interpenetrating network of the active layer blend that reduces the occurrence of trap sites, which, in turn, limits the Auger recombination rates. The QD-doped TFOSCs catalyzed with solvent additives displayed an enhanced overall photovoltaic parameter, which is quite appreciable in comparison with that of the pristine devices.

Multi-functionally ferroelectric polymer promotes highly-efficient large-area organic solar cells with excellent comprehensive performance

Developing high-performance active layer with excellent comprehensive performance is very crucial for the commercialization of organic solar cells (OSCs). Here, we demonstrate the multi-function of ferroelectric polymer polyvinylidene fluoride (PVDF) in improving the device comprehensive performance including device efficiency, stability, green-solvent large-area printing and mechanical property. Addition of PVDF not only enhances the build-in field to promote charge kinetics, but also develops robust network through strong interaction and chain entanglement between polymer donor and PVDF. Importantly, such robust network effectively protects the active layer from excessive flushing/swelling between D/A component to optimize layer-by-layer (LBL) deposition, induce a favorable vertical phase distribution and prolong the film-forming process, consequently facilitating green-solvent blade-coating printing, improving device efficiency and stability, and enhancing device mechanical flexibility. Due to the multiple advantages of PVDF, the PM6/BTP-eC9 obtains an excellent efficiency of 18.35% for BTP-eC9-based LBL devices. By blade-coating printing with green solvent, one of the highest efficiencies of 16.40% is achieved for large-area (1.21 cm2) binary device. Particularly, toughness is used to comprehensively evaluate mechanical property of OSCs, showing significant improvement with simultaneously enhanced fracture strength and tensile strain, and enabling small molecule-based system even have comparable mechanical flexibility and comprehensive performance to the all-polymer system.