Power Conversion Efficiency Research Articles

Modulating Molecular Interaction of Zwitterion Toward Rational Interface Engineering of Perovskite Solar Cells

AbstractPassivation of perovskite crystals is a crucial strategy to improve the efficiency and stability of perovskite solar cells (PSCs). Zwitterions, which contain both positive and negative charges in the molecule, can be used to passivate perovskite crystals. However, these materials strongly interact with each other, resulting in extremely low solubility in common organic solvents. The low solubility of zwitterions hinders the formation of uniform films, which negatively affects perovskite crystal growth. In this study, a liquid‐type zwitterion (LTZ) is synthesized by modulating intermolecular interactions of the zwitterion (3‐(1‐Pyridinio)‐1‐propanesulfonate). By suppressing intermolecular interactions, the solubility and processibility of the zwitterion in common organic solvents are successfully improved. The well‐distributed LTZ‐treated films are obtained, resulting in better electrical properties for the PSCs compared to solid‐type zwitterion‐based devices. With these characteristics, the resulting device achieves a power conversion efficiency of 24.9% with excellent thermal stability (under 60 °C and N2 atmosphere), maintaining over 80% of its initial efficiency for 1968 h. In addition, the PSC module (active area of 32.7 cm2) achieves an improved efficiency of 19.86% with high open‐circuit voltage and fill factor. The results suggest that interface engineering with an LTZ has the potential to fabricate efficient and stable PSCs.

Thermal Stability Analysis of Formamidinium–Cesium‐Based Lead Halide Perovskite Solar Cells Fabricated under Air Ambient Conditions

The instability of perovskite solar cells (PSCs) remains a major bottleneck for their commercialization, with thermal instability posing a major concern, given the inevitable presence of heat in photovoltaic devices. Mixed‐cation/halide perovskites demonstrate enhanced stability and efficiency compared to single‐cation/halide perovskites. Identifying the optimal perovskite composition capable of withstanding high temperatures for longer durations is crucial for the development of thermally stable PSCs. This study provides valuable insights into the optimization of mixed‐cation/halide perovskites to enhance the thermal and structural stability of perovskite films. By systematically varying the Cs content in FA1−yCsyPb(I0.85Br0.15)3 (0 < y < 25)‐based perovskite, it is observed that controlling the Cs content allows precise modulation of crystal orientation in perovskite film with 10% Cs obtained as the optimal value. The perovskite film containing 10% Cs not only exhibits reduced microstrain but also demonstrates enhanced thermal stability during testing at 85 °C under controlled humidity. Furthermore, planar PSCs are fabricated using FA0.90Cs0.10Pb(I0.85Br0.15)3 as the absorber layer and TOP‐3 as the hole‐transporting material, achieving a promising power conversion efficiency (PCE) of 17.70%. Impressively, the unencapsulated devices retain 95% of their initial PCE after 1000 h of dark storage under ambient conditions.

Endothermic Charge Separation Occurs Spontaneously in Non-Fullerene Acceptor/Polymer Bulk Heterojunction.

Organic photovoltaics (OPVs) based on non-fullerene acceptors (NFAs) have achieved a power conversion efficiency close to 20%. These NFA OPVs can generate free carriers efficiently despite a very small energy level offset at the donor/acceptor (D/A) interface. Why these NFAs can enable efficient charge separation (CS) with low energy losses remains an open question. Here, the CS process in the PM6:Y6 bulk heterojunction (BHJ) is probed by time-resolved two-photon photoemission (TR-TPPE) spectroscopy. We found that the CS, the conversion from bound charge transfer (CT) excitons to free carriers, is an endothermic process with an enthalpy barrier of 0.15eV. The CS can occur spontaneously despite being an endothermic process, which implies that it is driven by entropy. We further argue that the morphology of the PM6:Y6 film and the anisotropic electron delocalization restrict the electron and hole wavefunctions within the CT exciton such that they can primarily contact each other through point-like junctions. This configuration can maximize the entropic driving force. This article is protected by copyright. All rights reserved.

Multi-component Copolymerized Donorsenable Frozen Nano-morphology and Superior Ductility for EfficientBinary Organic Solar Cells.

Multi-component copolymerized donors (MCDs)have gained significant interest and have been rapidly developed in flexible organic solar cells (f-OSCs) in recent years. However, ensuring the power conversion efficiency (PCE) of f-OSCs while retaining ideal mechanical properties remains an enormous challenge. The fracture strain (FS) value of typical high-efficiency blend films is generally less than 8%, which is far from the application standards of wearable photovoltaic devices. Therefore, we developed a series of novel MCDs after meticulous molecular design. Among them, the consistent MCD backbone and end-capped functional group formed a highly conjugated molecular plane, and the solubilization and mechanical properties were effectively optimized by modifying the proportion of solubilized alkyl chains. Consequently, due to the formation of entangled structures with a frozen blend film morphology considerably improved the high ductility of the active layer, P10.8/P20.2-TCl exhibited efficient PCE in rigid (18.53%) and flexible (17.03%) OSCs, along with excellent FS values (16.59%) in pristine films, meanwhile, the outstanding FS values of 25.18% and 12.3% were achieved by P10.6/P20.4-TCl -based pristine and blend films, respectively, which were one of the highest records achieved by end-capped MCD-based binary OSCs, demonstrating promising application to synchronize the realization of high-efficiency and mechanically ductile flexible OSCs.

Exploring the Interactions at the Interface: Tailoring Carbazole‐Based SAMs with Varying Functional Groups for Enhancing the Performance of Inverted Perovskite Solar Cells

Four different carbazole‐based self‐assembled molecules with different terminal groups have been designed and synthesised as hole‐selective contacts for inverted perovskite solar cells to investigate their interfacial interactions and, consequently, the performance of the devices. Using the carbazole core as a reference, we compared the effect of the thiophen‐2‐yl phenyl, or the hydroxymethyl phenyl attached to the core through a phenyl moiety, with that of the thiophene directly linked to the carbazole. These new self‐assembled molecules have been successfully synthesized using cost‐effective starting materials and a straightforward synthetic method, eliminating the need for expensive and complex purification processes. Subsequently, they have been applied as efficient hole‐selective contact in inverted perovskite solar cells, leading to an outstanding power conversion efficiency of 19.67% in the case of SAM5, containing a carbazole‐core substituted with double 2‐phenylthiophene side arms as functional group. The detailed characterization of the interface and the charge kinetics has allowed us to determine the effect of each substituent.This article is protected by copyright. All rights reserved.

Simulation of multijunction solar cell interfaces for enhancement of the power conversion efficiency

Simulation of multijunction solar cell interfaces for enhancement of the power conversion efficiency

Feasibility study on thin‐film PV laminates for road integration

AbstractIntegration of photovoltaics (PV) into the built environment (BIPV) and infrastructure (IIPV) is required to increase the installed capacity of PV worldwide, while still leaving sufficient area for other land uses. Although BIPV applications have proven to play a significant role in the energy transition, road integrated IIPV concepts are less developed and bring challenges in mechanical and electrical stability and safety that still need to be addressed. In this work, the feasibility of integrating thin‐film CIGS (Copper Indium Gallium Selenide) modules into road tiles is investigated. PV road stacks were produced by gluing CIGS laminates onto concrete tiles and covering them with epoxy and glass granulates to form impact‐ and anti‐skid layers. IV (current–voltage) characteristics show that, respectively, a thin and thick epoxy layer results in 2% and 6.6% relative loss in power conversion efficiency. Although a thin protective layer would be beneficial to the power conversion efficiency of road modules, raveling tests show increased risk for electrical failure when a thin top layer is used. Pull‐off tests showed that the weakest adhesive strength (0.8 N/mm2) is between the thin‐film laminate and concrete, offering sufficient adhesive strength to at least withstand light traffic loading. Raveling and wheel tracking tests show no mass loss and only minor deformation of the stack, respectively, indicating no real risk of raveling or rutting. Thermal cycling and damp heat exposure of the PV road tiles show that yellowing of the top layers can significantly reduce performance over longer periods of outdoor operation. Damp heat exposure after mechanical loading shows no indication of moisture ingress on any of the tested configurations, suggesting the proposed CIGS laminate stack is able to withstand light traffic loading. From the measurement results, it can be concluded that thin‐film CIGS modules are mechanically and electrically suitable for road integration. Power conversion efficiencies over 12% can be attained with this technology, indicating its potential for renewable energy generation in road infrastructure. Performance stability can especially benefit from alternative top layer materials that maintain high transparency over long lifetimes. Additionally, pilot tests are required to demonstrate the potential of the technology in a controlled outdoor environment.

Alleviating the Angular Dependence of Perovskite Solar Cells via Light‐Harvesting Nanostructure

Over the past decade, perovskite solar cells (PSCs) have witnessed a remarkable surge in power conversion efficiency (PCE). However, the electrical output performance of PSCs is dependent on the incident angle of solar radiation, and energy loss occurs during photovoltaic conversion when light impinges at angles. Herein, a perovskite‐light‐absorbed layer with inverse opal structure is used to fabricate PSCs and reduce the angular dependence of the performance. In the results, it is demonstrated that ordered periodic perovskite inverse opal (PVSK–IO) not only exhibits a remarkable slow‐photon effect for enhancing the absorption of sunlight near the photonic bandgap (PBG), but also promotes the carrier transfer by expanding the contact area with hole‐transport layer. Moreover, the slow‐photon region of PBG can be intentionally tuned by changing the direction of sunlight illumination, thereby more intuitively delaying and storing light in the PVSK–IO layer. As a consequence, the slow‐photon effect originated from the PVSK–IO structure efficiently improves the short‐circuit current density, resulting in a higher PCE than that of planar devices under the irradiation from different incident angles. In this research, a rational strategy is offered for enhancing the performance of PSCs while alleviating their angular dependence.

Enhanced optical and electrochemical properties of FeBTC MOF modified TiO2 photoanode for DSSCs application

In this work, iron based 1, 3, 5-tricarboxylic acid (FeBTC) was prepared via microwave-assisted method and incorporated into TiO2 via ultrasonic assisted method. The TiO2–FeBTC nanocomposites were characterized by XRD, FTIR, Raman, BET, FESEM, HRTEM, TGA, UV‒vis DRS and PL to understand their crystallographic, surface morphology, and optical characteristics. The Raman spectra showed a blue shift of Eg, A1g, and B1g peaks upon incorporation of FeBTC MOF onto TiO2. HRTEM and XRD analysis confirmed a mixture of TiO2 nanospheres and hexagonal FeBTC MOF morphologies with high crystallinity. The incorporation of FeBTC onto TiO2 improved the surface area as confirmed by BET results, which resulted in improved absorption in the visible region as a results of reduced bandgap energy from 3.2 to 2.84 eV. The PL results showed a reduced intensity for TiO2–FeBTC (6%) sample, indicating improved separation of electron hole pairs and reduced recombination rate. After fabrication of the TiO2–FeBTC MOF photoanode, the charge transfer kinetics were enhanced at TiO2–FeBTC MOF (6%) with Rp value of 966 Ω, as given by EIS studies. This led to high performance due to low charge resistance. Hence, high power conversion efficiency (PCE) value of 0.538% for TiO2–FeBTC (6%) was achieved, in comparison with other loadings. This was attributed to a relatively high surface area which allowed more charge shuttling and thus better electrical response. Conversely, upon increasing the FeBTC MOF loading to 8%, significant reduction in efficiency (0.478%) was obtained, which was attributed to sluggish charge transfer and fast electron–hole pair recombination rate. The TiO2–FeBTC (6%) may be a good candidate for use in DSSCs as a photoanode materials for improved efficiency.

An Acceptor–Donor–Acceptor Molecule Tailored Versatile Buffer Enabling Efficient and Stable Perovskite Solar Cells

AbstractInterface in perovskite solar cells (PSCs) is of vital importance because it dominates deep‐level defects and non‐radiative recombination, thus impacting both efficiency and stability further. Herein, a symmetrical acceptor–donor–acceptor (A–D–A) conjugated molecule with the core architecture of terthieno[3,2‐b hiophene and 2‐(3‐oxo‐2,3‐dihydro‐1 H‐inden‐1‐ylidene)malononitrile, named 6TIC, as a versatile buffer layer, is adopted to enhance photovoltaic performance and stability simultaneously. It is found that the conjugated molecule filling at grain boundaries and surface can not only chemically anchor with perovskite components to substantially eliminate interfacial defects and suppress detestable non‐radiative recombination, but also effectively improve the energy level alignment and facilitate charge transfer efficiency at the interface, resulting in an excellent power conversion efficiency of 24.81% with an admirable fill factor of 84.5%. Furthermore, benefiting from the unexceptionable surface protection effect of the hydrophobic buffer layer, greatly improved operational stability is delivered, with retaining 90% of initial efficiency for 960 h aging in a relative humidity of 60 ± 5% air and 1450 h aging under continuous 85 °C heating stress. This strategy may provide a new avenue for advancing high‐efficiency and stable PSCs.

Bandgap-universal passivation enables stable perovskite solar cells with low photovoltage loss.

The efficiency and longevity of metal-halide perovskite solar cells are typically dictated by nonradiative defect-mediated charge recombination. In this work, we demonstrate a vapor-based amino-silane passivation that reduces photovoltage deficits to around 100 millivolts (>90% of the thermodynamic limit) in perovskite solar cells of bandgaps between 1.6 and 1.8 electron volts, which is crucial for tandem applications. A primary-, secondary-, or tertiary-amino-silane alone negatively or barely affected perovskite crystallinity and charge transport, but amino-silanes that incorporate primary and secondary amines yield up to a 60-fold increase in photoluminescence quantum yield and preserve long-range conduction. Amino-silane-treated devices retained 95% power conversion efficiency for more than 1500 hours under full-spectrum sunlight at 85°C and open-circuit conditions in ambient air with a relative humidity of 50 to 60%.

Revealing the high-performance of a novel Ge-Sn-Based perovskite solar cell by employing SCAPS-1D

In this study, a novel Ge-Sn based perovskite solar cell (PSC) with the structure FTO/WS2/ FA0.75MA0.25Sn0.95Ge0.05I3/MoO3/Ag has been designed and thoroughly analyzed employing SCAPS-1D. Drawing attention from the work of Ito et al where a similar perovskite-based PSC displayed a poor performance of ∼ 4.48% PCE, in which a large conduction band offset (CBO) acts as a critical factor contributing to interfacial recombination and device deterioration. To address this issue, we presented WS2 as an electron transport layer (ETL) along with MoO3 as a hole transport layer (HTL), both possessing compatible CBO and valence band offset (VBO) with perovskite material. Through systematic simulations and optimizations, remarkable improvements in the PSC’s performance have been acquired, getting a power conversion efficiency (PCE) of 18.97%. The optimized structure involved a 50 nm MoO3 HTL, 350 nm FA0.75MA0.25Sn0.95Ge0.05I3 light-harvesting layer (LHL), and a 50 nm WS2 ETL. Bulk defect densities for the LHL and ETL were optimized to 1 × 1015 cm−3 and 1 × 1018 cm−3, respectively, significantly superior values than that of reported value in the literature. Particularly, the tolerable defect density of ETL has increased 1000 times more than the published literature. The interfacial tolerable trap density for MoO3/perovskite increased from 1 × 1014 cm−2 to 1 × 1016 cm−2. The study also explored the impact of defects on quantum efficiency, revealing a severe negative influence beyond a perovskite bulk defect density of 1 × 1017 cm−3. Light intensity analysis demonstrated a correlation between incident light reduction and device performance decay. Capacitance–Voltage (C-V) and Mott–Schottky (M-S) have been analyzed during the study. Finally, the total recombination of the optimized device concerning thickness has been analyzed along with the dark J-V characteristics. The comprehensive insights gained from this work are anticipated to accelerate the fabrication of mixed Ge-Sn based PSCs with improved efficiency, paving the way for commercialization in the photovoltaic industry.

A CMOS Rectifier with a Wide Dynamic Range Using Switchable Self-Bias Polarity for a Radio Frequency Harvester

This paper presents a switchable self-bias polarity on the CMOS complementary cross-coupled rectifier to improve the rectifier’s power conversion efficiency (PCE) profile across a wide input power (PIN) dynamic range. This technique achieves this by adaptively switching the polarity of the bias on the n-MOS to overdrive it during low PIN to improve the sensitivity and underdrive it during high PIN to suppress the shoot-through loss and the unnecessary discharge of the coupling capacitor. The popular self-biased p-MOS is also implemented further to reduce the reverse conduction loss during high PIN. The proposed rectifier is fabricated in a 40 nm CMOS process and operates at 900 MHz with a load of 50 kΩ. The proposed rectifier achieved a peak PCE of 72.1% and maintained a 0.8xPCEPEAK across a PIN dynamic range of 11.5 dB.

Eco-friendly guar gum composites as solid-state electrolytes

Solid-state Guar gum electrolytes were prepared through the solution casting technique, employing a composition of 70 % Guar gum and 30 % ZnSO4·7H2O(GZ3). Different weight concentrations of nano ZrO2 (2.5 %, 5 %, 7.5 %, and 10 %) were introduced into the present Guar gum electrolytes. As prepared ZrO2 nanofiller substituted Guar gum electrolytes were examined by XRD, FTIR, DSC, and SEM to evaluate the amorphous characteristics, complexation, glass transition temperature, and surface morphology, respectively. Electrochemical impedance was utilized to examine the frequency-dependent ionic conductivity and dielectric properties of prepared ZrO2 nanofiller-substituted Guar gum electrolytes. At a temperature of 100 °C, the Guar gum electrolyte with10 % Nano ZrO2 exhibited an ionic conductivity of 3.19 × 10−3 S/cm, whereas, at room temperature (RT), it recorded a value of 1.09 × 10−3 S/cm. The activation energy for these electrolytes varied within the range of 0.26 eV–0.39 eV. Furthermore, an investigation of the frequency-dependent dielectric properties revealed a significant tail in the low-frequency region and the presence of space charge polarization within the electrolyte. The study also explored the relaxation time and hopping mechanism through dielectric modulus parameters. Moreover, a flexible Zn-based electrochemical cell was fabricated using a formulation comprising 70 % Guar gum, 30 % Zinc salt, and 10 % Nano ZrO2. The outcomes revealed an open circuit voltage of 0.82V, a discharge rate of 0.04C sustained over 25 h, with an average current discharge rate of approximately 1.4 mA per hour, resulting in an electrochemical-specific capacity of around 45mAh/g. Additionally, a solar cell device was fabricated using Guar gum electrolytes, and the photovoltaic parameters were computed. The maximum overall power conversion efficiency (ƞ) reached 4.79, with short-circuit photocurrent density (Jsc) at 9.66 mA/cm2, open-circuit voltage (Voc) at 725 mV, and fill factor (FF) at 0.65.

Mitigating the Degradation of MAPbI3 Perovskite Solar Cells Under Continuous Light Soaking with ZnO@CdS:Epoxy Short‐Wavelength Sunlight‐Shielded Films

The stability of MAPbI3‐based (MA stands for methylammonium) perovskite solar cells (PVSCs) has been carefully examined by ZnO@CdS nanoparticle‐embedded epoxy films (EP‐ZC films), device encapsulation (of glass sheet and UV‐curing gel), and in different temperatures, 10 °C, room temperature (no temperature control), and 65 °C. EP‐ZC films are used for shielding the short wavelength of the sunlight (UV, near UV, violet, and deep blue) which causes the photodegradation of MAPbI3 and hence the decline of power conversion efficiency (PCE) of PVSCs. Some external quantum efficiency spectra of the device are recorded alongside of the 500 h continuous light‐soaking measurement of current density (J)−voltage (V) of the devices. The time‐of‐flight secondary‐ion mass spectroscopy analysis is performed for a quantitative comparison of the iodide derived from the degradation of MAPbI3 in the encapsulated devices with or without the light‐shielding EP‐ZC films at 10 °C and 65 °C, respectively. The EP‐ZC6 film shows the best protection for encapsulated PVSCs with 98% of the initial PCE at 10 °C after 500 h continuous light soaking. Herein, from the continuous light‐soaking results, one can prioritize the moisture, temperature, and light in the influence of the stability of PVSCs.

Buried Interface Passivation of Sn–Pb Narrow‐Bandgap Perovskite for Highly Efficient All‐Perovskite Tandem Solar Cells

All‐perovskite tandem solar cells (ATSCs) present a remarkable opportunity to overcome the Shockley–Queisser efficiency limit of single‐junction solar cells. However, the stability of ATSCs significantly lags that of their pure Pb‐based single‐junction counterparts. Recent studies have identified that the widely used poly(3,4‐ethylenedioxythiophene)‐poly(styrenesulfonate) (PEDOT:PSS) hole transport layer in narrow‐bandgap (NBG) tin–lead (Sn–Pb) perovskite solar cells (PSCs) hinders the efficiency and stability. Herein, a patching strategy to optimize the interface between perovskite and PEDOT:PSS is proposed. Both theoretical and experimental studies reveal that PenA+ and Ac− can decrease defect states at the interface and strengthen the binding between PEDOT:PSS and Sn–Pb perovskite. Furthermore, the pentylammonium acetate (PenAAc) interlayer improves carrier extraction and suppresses the oxidation of Sn2+ to Sn4+. With the PenAAc buried layer, the fabricated NBG PSCs obtain an impressive power conversion efficiency (PCE) of 21.86%, along with significantly enhanced device stability. By integrating the buried passivated NBG Sn–Pb perovskite with a 1.75 eV wide‐bandgap PSC, the two‐terminal ATSC achieves a PCE of 26.54%. This work provides a valuable approach to fabricate efficient and stable NBG PSCs.

A Difluoro-Methoxylated Ending-Group Asymmetric Small Molecule Acceptor Lead Efficient Binary Organic Photovoltaic Blend.

Developing a new end group for synthesizing asymmetric small molecule acceptors (SMAs) is crucial for achieving high-performance organic photovoltaics (OPVs). Herein, an asymmetric small molecule acceptor, BTP-BO-4FO, featuring a new difluoro-methoxylated end-group is reported. Compared to its symmetric counterpart L8-BO, BTP-BO-4FO exhibits an upshifted energy level, larger dipole moment, and more sequential crystallinity. By adopting two representative and widely available solvent additives (1-chloronaphthalene (CN) and 1,8-diiodooctane (DIO)), the device based on PM6:BTP-BO-4FO (CN) photovoltaic blend demonstrates a power conversion efficiency (PCE) of 18.62% with an excellent open-circuit voltage (VOC) of 0.933V, which surpasses the optimal result of L8-BO. The PCE of 18.62% realizes the best efficiencies for binary OPVs based on SMAs with asymmetric end groups. A series of investigations reveal that optimized PM6:BTP-BO-4FO film demonstrates similar molecular packing motif and fibrillar phase distribution as PM6:L8-BO (DIO) does, resulting in comparable recombination dynamics, thus, similar fill factor. Besides, it is found PM6:BTP-BO-4FO possesses more efficient charge generation, which yields better VOC-JSC balance. This study provides a new ending group that enables a cutting-edge efficiency in asymmetric SMA-based OPVs, enriching the material library and shed light on further design ideas.

Effect of UV‐ozone treatment for KCl interlayer in perovskite solar cells

AbstractThe performance of perovskite solar cells (PSCs) is significantly governed by the interface of perovskite layer. Therefore, a great deal of attention has been paid to the interface engineering of perovskite layer to improve the performance of PSC. In the meantime, KCl is one of the popular molecules being utilized for the interface treatment between SnO2 and perovskite. In this study, we investigate the effect of UV‐ozone (UVO) treatment of KCl interlayer on the photovoltaic performance. A device employing UVO‐treated KCl shows a higher power conversion efficiency mainly based on an increased open‐circuit voltage (VOC). Ultraviolet photoelectron spectroscopy analysis indicates that the UVO treatment induces a rearrangement of energy level at the interface, being responsible for the increase in VOC. Accordingly, an increased charge recombination resistance is evidenced by impedance spectroscopy owing to the inhibited recombination at the SnO2 and perovskite interface by the aid of the aligned energy level.

Efficiency enhancement of non-fullerene organic solar cells using PEDOT:PSS diluted with alcohol solvents as the hole transport layer

The poly3,4-ethylenedioxythiophene) poly(styrene sulfonate) (PEDOT:PSS) hole transport layer (HTL) has always played a crucial role in achieving high-efficiency organic solar cells (OSCs) owing to its unique advantages of suitable energy levels and high optical transparency. However, the inherent insulation and easy aggregation property of PSS results in relatively low conductivity and high surface roughness of the PEDOT:PSS film, which is unfavorable for charge transport and the morphology of the top layer. To address these problems, we use PEDOT:PSS diluted in a series of alcoholic solvents and evaluate them on the PM6:Y6 system. Among these, the PM6:Y6 devices using PEDOT:PSS modified with ethanol as the HTL demonstrate the best vertical phase segregation and carrier extraction. In addition, the PEDOT:PSS film with added ethanol also has the smoothest surface compared to those diluted in the other alcoholic solvents. Finally, a high power conversion efficiency of 18.13% was obtained with the PM6:Y6 devices based on PEDOT:PSS modified by ethanol. This work provides a sufficient reference for the alcoholic modification of PEDOT:PSS and also proposes a feasible solution for high-efficiency OSCs.

One-Stone-for-Two-Birds Method to Improve the SnO2 Layers for High Power-per-Weight Flexible Perovskite Solar Cell Mini-modules.

Maintaining the power conversion efficiency (PCE) of flexible perovskite solar cells (fPSCs) while decreasing their weight is essential to utilize their lightweight and flexibility as much as possible for commercialization. Strengthening the interfaces between functional layers, such as flexible substrates, charge transport layers, and perovskite active layers, is critical to addressing the issue. Herein, we propose a feasible and one-stone-for-two-birds method to improve the electron transport layer (ETL), SnO2, and the interface between the ETL and perovskite layer simultaneously. In detail, poly(acrylate ammonium) (PAAm), a low-cost polymer with a long chain structure, is added into the SnO2 aqueous solution to reduce the aggregation of SnO2 nanoparticles, resulting in the deposition of a conformal and high-quality ETL film on the tin-doped indium oxide film surface. Simultaneously, PAAm addition can effectively regulate the crystallization of the perovskite films, strengthening the interface between the SnO2 film and the buried surface of the perovskite layer. The outstanding PCEs of 22.41% on small-scale fPSCs and 18.54% on fPSC mini-modules are among the state-of-the-art n-i-p type fPSCs. Moreover, the fPSC mini-module on the 20 μm-thick flexible substrate shows a comparable PCE with that of the fPSC mini-module on the 125 μm-thick flexible substrate, exhibiting a high power-to-weight of 5.097 W/g. This work provides an easy but essential direction for further applications of fPSCs in diverse scenarios.