Energy Level Alignment Research Articles

Flexible Substrate-Compatible and Efficiency-Improved Quantum-Dot Light-Emitting Diodes with Reduced Annealing Temperature of NiOx Hole-Injecting Layer

The growing demand for wearable and attachable displays has sparked significant interest in flexible quantum-dot light-emitting diodes (QLEDs). However, the challenges of fabricating and operating QLEDs on flexible substrates persist due to the lack of stable and low-temperature processable charge-injection/-transporting layers with aligned energy levels. In this study, we utilized NiOx nanoparticles that are compatible with flexible substrates as a hole-injection layer (HIL). To enhance the work function of the NiOx HIL, we introduced a self-assembled dipole modifier called 4-(trifluoromethyl)benzoic acid (4–CF3–BA) onto the surface of the NiOx nanoparticles. The incorporation of the dipole molecules through adsorption treatment has significantly changed the wettability and electronic characteristics of NiOx nanoparticles, resulting in the formation of NiO(OH) at the interface and a shift in vacuum level. The alteration of surface electronic states of the NiOx nanoparticles not only improves the carrier balance by reducing the hole injection barrier but also prevents exciton quenching by passivating defects in the film. Consequently, the NiOx-based red QLEDs with interfacial modification demonstrate a maximum current efficiency of 16.1 cd/A and a peak external quantum efficiency of 10.3%. This represents a nearly twofold efficiency enhancement compared to control devices. The mild fabrication requirements and low annealing temperatures suggest potential applications of dipole molecule-modified NiOx nanoparticles in flexible optoelectronic devices.

The role of interface energetics in Sb2Se3 thin film solar cells

We comprehensively simulated the interface energetics at the Sb2Se3/CdS interfaces and showed its impact on device performance. The interface discontinuity, band bending at interface and energy level alignment generates interfaces issues and must be optimized for an optimal device performance. The design parameters for controlling interface. Metal contact work function preferably higher than electron affinity (EA) and Fermi level (EF) combined (EA + EF), should result in near Ohmic behaviour of contact. Secondly electron affinity of buffer could be tuned to achieve small positive conduction bandoffset (spike barrier) at absorber/buffer interface which lowers the chances of recombination through interface states. A pn + configuration with highly doped buffer layer, as compared to p-absorber, is favourable as it will extend depletion in absorber, providing additional drift to photo-generated carriers. Lastly, acceptor defect at Sb2Se3-CdS interface generate surface inversion and detrimental to performance. Donor defects occupying interface states are preferred condition for optimal device performance. We have compiled the optimal ranges for these controlling parameters, to achieve theoretically ideal values of energy level alignment and energetics, leading to optimal performance.

In Situ Electrochemical Cobalt Doping in Perovskite-Structured Lanthanum Nickelate Thin Film Toward Energy Conversion Enhancement of Polymer Solar Cells.

This study demonstrates that the electrochemical doping of lanthanum nickelate (LNO) with cobalt ions is a promising strategy for enhancing its physical and electrochemical properties, which are critical for energy storage and conversion devices. LNO emerges as a promising hole transport layer (HTL) in solar cells due to its stability, large band gap, and high transparency. Nevertheless, its low conductivity and improperly aligned band positions are persistent problems. Here, in a pioneering endeavor, Co-doped LNO thin films were synthesized electrochemically and applied as the HTL in polymer solar cells (PSCs). Characterization revealed the impact of Co doping on the electrochemical, structural, morphological, and optical properties of LNO thin films. Depending on the Co doping level, PSCs based on 10 mol % Co-doped LNO outperformed pure LNO, achieving a champion efficiency of 6.11% with enhanced short-circuit current density (12.84 mA cm-2), fill factor (68%), open-circuit voltage (0.70 V), and external quantum efficiency (82.6%). This enhancement resulted from decreased series resistance, refined surface morphology, minimized trap-assisted recombination, enhanced conductivity, increased charge carrier production, favorable energy level alignment, and improved current extraction facilitated by LNC0.10O HTL. Moreover, the unencapsulated PSC-LNC0.10O long-term stability notably improved and retained 86% of its initial PCE after 450 h storage in ambient air, 82% after being continuously heated to 85 °C for 300 h, and 80% after operating at maximum power point for 300 h. These findings offer a straightforward approach to enhancing PSC performance through Co doping of LNO, supported by density functional theory (DFT) calculations that validate the experimental results and confirm the improvement in optical properties and stability of PSCs as an HTL.

Utilizing a Carbazole‐Incorporated Regioisomeric Synthesis Strategy to Design Hole Transporting Materials for Perovskite Solar Cells

AbstractTwo new p‐type molecules, namely TAT‐TY3 and TAT‐TY4, featuring triazatruxene endcaps and carbazole π‐bridges, were synthesized. The photophysical and electrochemical properties of synthesized materials were comparatively investigated based on their 2,7‐ and 3,6‐carbazole conjugation pathways. Optical characterizations revealed the impact of non‐bonding electron delocalization of triazatruxene through carbazole moieties, resulting in a significant increase in absorption intensity corresponding to n‐π* energy transitions and a red shift of triazatruxene moieties. Consequently, the optical band gaps of TAT‐TY3 and TAT‐TY4 were measured at 3.0 and 3.2 eV, respectively. Moreover, the molecules′ first oxidation potentials exhibited a drastic difference due to the electrochemical behavior of 2,7‐ and 3,6‐carbazole moieties. The highest occupied molecular orbital (HOMO) level for TAT‐TY3 was measured to be −5.02 eV, while for TAT‐TY4, it was measured as −4.67 eV. Hole‐extraction properties were explored using steady‐state and time‐resolved photoluminescence spectroscopy, revealing enhanced charge transfer between the TAT‐TY3/Perovskite interface due to the better alignment of HOMO energy levels. The photovoltaic performances of the hole‐transporting materials (HTMs) were successfully characterized in triple‐cation perovskite solar cells and efficiencies of up to 17.9 %, 16.2 %, and 9.8 % were achieved for Spiro‐OMeTAD, TAT‐TY3, and TAT‐TY4, respectively.

Fabrication of Efficient and Simple-Structured Perovskite Solar Cells Using a Multifunctional Biocolina Surface Treatment.

The electron transport layer (ETL)-free perovskite solar cells (PSCs) have gained significant interest by simplifying the manufacture process and reducing the time/energy required for the fabrication of ETLs. Unfortunately, the performance of these ETL-free PSCs still lags behind those of the conventional counterparts due to the slow electron extraction and undesired interfacial charge recombination loss at the buried interface. In this work, a facile and multifunctional biocolina thin layer is incorporated on the bottom electrodes to regulate the interface energy level alignment by forming an interface dipole layer, resulting in a suppressed nonradiative recombination and an improved charge extraction. Furthermore, the biocolina thin layer possess the capability to passivate the surface defects within the perovskite films while simultaneously facilitate the formation of perovskite crystals. Consequently, a remarkable enhancement in photovoltaic performance is observed in the biocolina-based ETL-free PSCs with an increase from 15.96 % to an outstanding 20.01 %. Additionally, the biocolina extends the stability and relieves the hysteresis effect through the interface defect passivation and inhibition of interface charge accumulation. This research contributes to the development of cost-effective, simplified designs for highly efficient ETL-free PSCs by modifying the bottom electrodes.

Effect of Bridging Manner on the Transport Behaviors of Dimethyldihydropyrene/Cyclophanediene Molecular Devices.

A molecule-electrode interface with different coupling strengths is one of the greatest challenges in fabricating reliable molecular switches. In this paper, the effects of bridging manner on the transport behaviors of a dimethyldihydropyrene/cyclophanediene (DHP/CPD) molecule connected to two graphene nanoribbon (GNR) electrodes have been investigated by using the non-equilibrium Green's function combined with density functional theory. The results show that both current values and ON/OFF ratios can be modulated to more than three orders of magnitude by changing bridging manner. Bias-dependent transmission spectra and molecule-projected self-consistent Hamiltonians are used to illustrate the conductance and switching feature. Furthermore, we demonstrate that the bridging manner modulates the electron transport by changing the energy level alignment between the molecule and the GNR electrodes. This work highlights the ability to achieve distinct conductance and switching performance in single-molecular junctions by varying bridging manners between DHP/CPD molecules and GNR electrodes, thus offering practical insights for designing molecular switches.

Self‐doped conjugated polymers with electron‐deficient quinone units for enhanced electron transport in highly efficient organic solar cells

AbstractOrganic solar cells (OSCs) have attracted significant attention as a burgeoning flexible technology, owing to their advanced power conversion efficiencies. Moreover, interface materials play a crucial role in optimizing energy level alignment between the active layer and electrodes, thereby enhancing carrier extraction within the device and improving efficiency. However, current methodologies for fabricating electron‐transport materials with superior mobility are still limited compared with those for hole‐transport materials. In this study, a benzodifurandione (BFDO)‐derived building block with quinone resonance property and strong electron‐withdrawing capability was synthesized. Two conjugated polymers, namely PBFDO‐F6N and PBFDO‐F6N‐Br, were prepared, both of which exhibited good electron mobility and exceptional interface modification capabilities. A comprehensive investigation of the interaction between the interface layer and the active layer revealed that PBFDO‐F6N induced doping at the acceptor interface. Additionally, the high mobility of PBFDO‐F6N facilitated efficient carrier extraction at the interface. Consequently, the application of PBFDO‐F6N as the cathode interface layer for PM6:BTP‐eC9‐based OSC devices resulted in a remarkable efficiency of 18.11%. Moreover, the device efficiency remained at ∼96% even at a PBFDO‐F6N interface thickness of 50 nm, demonstrating the great potential of this material for large‐scale device preparation.

Anions Regulation of 1D Perovskite Intrusion-Behavior for Efficient and Stable Perovskite Solar Cells.

Constructing a 1D/3D perovskite heterojunction has recently emerged as a prevalent approach for elevating the efficiency and stability of perovskite solar cells (PSCs), due to the excellent defect-passivation capacity and enhanced resistance to water and oxygen of 1D perovskite. However, the 1D perovskite commonly exhibits much poorer charge carrier transport ability when compared with its 3D counterpart. Tailoring the intrusion depth of a 1D perovskite into the 1D/3D heterojunction is thus of key importance for PSCs but remains a great challenge. We introduce herein a novel anion-regulation strategy that can effectively tune the intrusion behavior of 1D perovskite into 3D perovskite to form a 1D/3D heterojunction with gradual structure and gradient energy-level alignment. This gradual 1D/3D-perovskite interface leads to outstanding defect passivation performance, together with a desired balance between charge transport and moisture/oxygen blocking. Consequently, the PSCs with a 1D/3D perovskite heterojunction resulting from tetra-n-butylammonium acetate (TBAAc) treatment yield a remarkable enhancement in power conversion efficiency (PCE) from 18.4 to 20.1%. The unencapsulated device also demonstrates excellent stability and retains 90% of its initial PCE after 2400 h of storage in the air atmosphere with 30 ± 5% humidity at 25 ± 5 °C.

Rational Design and Engineering of Terminal Functional Groups in Dibenzothiophene‐Diphenylamine Small Molecular Electron Donors for Enhanced Photovoltaic Efficiency in All‐Small‐Molecule Organic Solar Cells

AbstractAll‐small‐molecule organic solar cells (ASM‐OSCs) offer advantages like well‐defined molecular structures and excellent reproducibility. However, lower photovoltaic efficiencies hinder their adoption due to limitations in designing small molecular electron donors (SMEDs) with optimal energy levels, light absorption, and optoelectronic properties. The present study addresses this gap by rationally designing a series of SMEDs (DBT‐2FA1 to DBT‐2FA6) through terminal acceptors engineering into dibenzothiophene core with diphenylamine side donors for potential applications in ASM‐OSCs. Density functional theory simulations are carried‐out to establish structure‐property relationships based on structural, electrochemical, photophysical, and charge transfer (CT) properties. Results show that the SMEDs exhibit low‐lying HOMOs for suitable energy level alignment with benchmark Y6 acceptor, promoting open‐circuit voltage and charge separation. The panchromatic absorption spectra covering Vis‐NIR region and maximum light harvesting efficiency are beneficial for high current‐density in ASM‐OSCs. Notably, the push‐pull mechanism within SMEDs results in dominant intramolecular CT with above 70% CT excitations. Whereas, a moderate variation in dipole moments and electrostatic potential differences with acceptor material led to 99.9% intermolecular CT, thus ensuring robust exciton dissociation and efficient photocurrent generation. Overall, this work provides a molecular‐level understanding of designing novel SMEDs and their compatibility with acceptor materials for developing future high‐performance ASM‐OSCs.

Lowering Charge Transport Barriers by Eliminating the Electric Double Layer Residues to Reconstruct Adjacent SnO2 Nanocrystals for High‐Efficiency Flexible Perovskite Solar Cells

AbstractThe sol–gel method is efficient and cost‐effective for synthesizing SnO2 sol, wherein SnO2 nanocrystallites (NCs) are stabilized by electric double‐layer of solvated ions tightly bound to their surface. However, this strong binding makes the removal of electric double‐layer residues from the SnO2 electron transport layer (ETL) to be difficult at low temperatures. This hinders both the close contact and subsequent growth among adjacent SnO2 NCs, leading to severe carriers scattering at grain boundary, adversely affecting the electrical properties of SnO2 ETL. Herein, SnO2 sol is synthesized via an ethanol‐based sol–gel method and aqueous ammonia (NH3·H2O) is introduced to effectively clean stubborn electric double‐layer residues within the SnO2 ETL at a low temperature (80 °C). Removing residues reduces the gap among adjacent SnO2 NCs and promotes further reconstructed growth through oriented attachment (OA), thereby reducing the number of grain boundaries. Hence, the energy barriers for electron transport decrease within the SnO2 ETL. Furthermore, MHP prepared on the treated ETL has fine‐tuned energy level alignment, improving the electron extraction capacity. Consequently, flexible perovskite solar cells (f‐PSCs) incorporating this ETL achieved a notable increase in power conversion efficiency, rising from 19.16% to 23.71%, as well as superior mechanical stability.

Enhanced performance of perovskite solar cell via up-conversion YLiF4:Yb, Er nanoparticles

We report a simple and effective method for producing lanthanide ion-doped lithium-fluoride-based nanocrystals (YLiF4). We utilized those nanoparticles for up-conversion in fabricated perovskite solar cells. The obtained results shows that the up-conversion YLiF4:Yb, Er nanoparticles improve alignment of energy levels at interface between titanium dioxide and perovskite layer. This increases power conversion efficiency of fabricated perovskite solar cells from 19.45 % to 21.32 %. To enhance comprehension of the recombination mechanism and its correlation with the conduction band offset and defects, device models are additionally integrated into the SCAPS simulator. Subsequently, the obtained J-V simulation outcomes exhibit a favorable concordance with the experimental observations.

Enhancement of Efficiency of Perovskite Solar Cells with Hole-Selective Layers of Rationally Designed Thiazolo[5,4-d]thiazole Derivatives.

We introduce thiazolo[5,4-d]thiazole (TT)-based derivatives featuring carbazole, phenothiazine, or triphenylamine donor units as hole-selective materials to enhance the performance of wide-bandgap perovskite solar cells (PSCs). The optoelectronic properties of the materials underwent thorough evaluation and were substantially fine-tuned through deliberate molecular design. Time-of-flight hole mobility TTs ranged from 4.33 × 10-5 to 1.63 × 10-3 cm2 V-1 s-1 (at an electric field of 1.6 × 105 V cm-1). Their ionization potentials ranged from -4.93 to -5.59 eV. Using density functional theory (DFT) calculations, it has been demonstrated that S0 → S1 transitions in TTs with carbazolyl or ditert-butyl-phenothiazinyl substituents are characterized by local excitation (LE). Mixed intramolecular charge transfer (ICT) and LE occurred for compounds containing ditert-butyl carbazolyl-, dimethoxy carbazolyl-, or alkoxy-substituted triphenylamino donor moieties. The selected derivatives of TT were used for the preparation of hole-selective layers (HSL) in PSC with the structure of glass/ITO/HSLs/Cs0.18FA0.82Pb(I0.8Br0.2)3/PEAI/PC61BM/BCP/Ag. The alkoxy-substituted triphenylamino containing TT (TTP-DPA) has been demonstrated to be an effective material for HSL. Its layer also functioned well as an interlayer, improving the surface of control HSL_2PACz (i.e., reducing the surface energy of 2PACz from 66.9 to 52.4 mN m-1), thus enabling precise control over perovskite growth energy level alignment and carrier extraction/transportation at the hole-selecting contact of PSCs. 2PACz/TTP-DPA-based devices showed an optimized performance of 19.1 and 37.0% under 1-sun and 3000 K LED (1000 lx) illuminations, respectively. These values represent improvements over those achieved by bare 2PACz-based devices, which attained efficiencies of 17.4 and 32.2%, respectively. These findings highlight the promising potential of TTs for the enhancement of the efficiencies of PSCs.

Stable pure-green organic light-emitting diodes toward Rec.2020 standard

Manipulating dynamic behaviours of charge carriers and excitons in organic light-emitting diodes (OLEDs) is essential to simultaneously achieve high colour purity and superior operational lifetime. In this work, a comprehensive transient electroluminescence investigation reveals that incorporating a thermally activated delayed fluorescence assistant molecule with a deep lowest unoccupied molecular orbital into a bipolar host matrix effectively traps the injected electrons. Meanwhile, the behaviours of hole injection and transport are still dominantly governed by host molecules. Thus, the recombination zone notably shifts toward the interface between the emissive layer (EML) and the electron-transporting layer (ETL). To mitigate the interfacial carrier accumulation and exciton quenching, this bipolar host matrix could serve as a non-barrier functional spacer between EML/ETL, enabling the distribution of recombination zone away from this interface. Consequently, the optimized OLED exhibits a low driving voltage, promising device stability (95% of the initial luminance of 1000 cd m−2, LT95 > 430 h), and a high Commission Internationale de L’Éclairage y coordinate of 0.69. This indicates that managing the excitons through rational energy level alignment holds the potential for simultaneously satisfying Rec.2020 standard and achieving commercial-level stability.

Polysaccharide‐Modified SnO2 for Highly Efficient Perovskite Solar Cells

Tin oxide (SnO2) has been demonstrated as a promising electron transport material for perovskite solar cells (PSCs) due to its low‐temperature process and high charge extraction ability. However, the key to improving the internal performance of PSCs toward unity lies in the ability of enhancing bulk SnO2 quality and reducing the energy level mismatch between SnO2 and perovskite layer. Herein, a facile and effective strategy to simultaneously functionalize SnO2 structure by sodium alginate (SA) polysaccharide compound is reported. The investigations reveal that SA leads to the formation of nanosynapse structure of SnO2 films, which allows the aligned energy levels and suppressed charge recombination, significantly enhancing carrier extraction and transport. Consequently, CsMAFAPb(IxBr1−x)3 and CsPbI2Br solar cells achieve a remarkable power conversion efficiency of 24.11% and 16.90%, respectively, based on SnO2‐SA electron transport layers (ETLs). This work offers a facile and effective way to fabricate high‐performance SnO2 ETL in PSCs.

Studies of optoelectrical properties of Mn-doped ZnO nanostructure for supercapacitor and photodetector applications

The transition metal Manganese (Mn)-doped Zinc Oxide (ZnO) nanoparticles were synthesized using the sol-gel method. The nanomaterials ZnO and Zn1-xMnxO (x=0–0.15) formation, their crystal structure, and morphological properties were confirmed by X-ray Diffraction (XRD) and Scanning Electron Microscope (SEM) analysis of the materials. All the studied materials show hexagonal wurtzite structure with the particle size in nanometres. The optical properties of transition metal Mn-doped ZnO nanomaterials were explored by the absorption and transmission spectra. The band gap of the nanomaterials decreases with the increase of Mn doping concentration from 3.01 to 3.26 eV. The mobility and electrical conductivity of the Mn-doped ZnO thin films show a decreasing trend with the increase of Mn doping concentration in ZnO. The Mn-doped materials were investigated for supercapacitor and photodiode applications. The Zn0.90Mn0.10O nanomaterials show the maximum specific capacitance, power and energy density of ∼ 220 F/g, 2202 W/kg and 1.15 Wh/kg, respectively. The electrochemical properties confirm that the doping of ZnO opens a new window for its application in energy storage devices. The ZnO and Mn-doped ZnO were used as an electron transport layer in perovskite MAPbI3 photodiodes. Under the Illumination of blue (465 nm) light, the highest detectivity of undoped ZnO perovskite photodiode is ∼4.5×1010 Jones and doped ZnO perovskite photodiode is 0.7×1010 Jones, respectively. The low mobility of charges and unfavorable energy level alignment of Mn-doped ZnO with MAPbI3 thin films is the reason for the decrease in photo detectivity. Our studies demonstrate that the Mn-doped ZnO nanomaterials and their thin films have avenues for potential application in energy storage devices and photodiodes of perovskite MAPbI3.

Improving Thermal Stability of High-Efficiency Methylammonium-Free Perovskite Solar Cells via Chloride Additive Engineering.

Tin dioxide (SnO2), in perovskite solar cells (PSCs), stands out as the material most suited to the electron transport layer (ETL), yielding advantages with regard to ease of preparation, high mobility, and favorable energy level alignment. Nonetheless, there is a chance that energy losses from defects in the SnO2 and interface will result in a reduction in the Voc. Consequently, optimizing the interfaces within solar cell devices is a key to augmenting both the efficiency and the stability of PSCs. Herein this present study, we introduced butylammonium chloride (BACl) into the SnO2 ETL. The resulting optimized SnO2 film mitigated interface defect density, thereby improving charge extraction. The robust bonding capability of negatively charged Cl- ions facilitated their binding with noncoordinated Sn4+ ions, effectively passivating defects associated with oxygen vacancies and enhancing charge transport within the SnO2 ETL. Concurrently, doped BA+ and Cl- diffused into the perovskite lattice, fostering perovskite grain growth and reducing the defects in perovskite. In comparison to the control device, the Voc saw a 70 mV increase, achieving a champion efficiency of 22.86%. Additionally, following 1000 h of ambient storage, the unencapsulated device based on SnO2 preburied with BACl retained around 90% of its initial photovoltaic conversion efficiency.

19.36% Efficiency Organic Solar Cells Based on Low‐Cost Terpolymer Donors with Simple Molecular Structures

AbstractLow cost and high performance are key elements for the industrialization of organic solar cells (OSCs). In view of this, developing highly‐efficient organic photovoltaic molecules with simple chemical structure is one of the most effective countermeasures. Herein, three simple‐structure terpolymers PTQ12‐5, PTQ12‐10, and PTQ12‐15 are designed and synthesized, by embedding difluoro‐substituted bithiophene (2T‐2F) unit into the backbone of low‐cost and high‐efficiency polymer PTQ10. The synthesis of three terpolymers contains only two‐step synthetic routes and over 85% synthetic yields from cheap raw compounds, thus exhibiting distinctly low‐cost characteristic. Remarkably, PTQ12‐5 shows significantly higher absorbance coefficient and hole mobility than PTQ10. Consequently, PTQ12‐5‐based OSCs shows more efficient exciton dissociation and charge transfer, suppressed carrier recombination, tighter molecular π‐π stacking, and faster and more balanced charge transport, thus demonstrates a significantly improved efficiency of 18.77% than that of PTQ10‐based device (18.03%). Moreover, an outstanding efficiency of 19.36% is achieved in PTQ12‐5‐based ternary device by further modulating the energy level alignment and blending features of photoactive molecules, which is the highest efficiency of OSCs based on low‐cost polymers to date. This work has significant implications for guiding the design of low‐cost and high‐performance organic photovoltaic materials.

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.

Improving Thermal Stability of Perovskite Solar Cells by Suppressing Ion Migration

Ion migration presents a formidable obstacle to the stability and performance of perovskite solar cells (PSCs), hindering their progress toward commercial feasibility. Herein, the degradation mechanism of PSCs caused by iodide ion migration, which leads to abnormal changes in photoluminescence transients at the buried interface of perovskite films, is investigated. In light of this problem, a novel strategy is proposed to mitigate ion migration by introducing poly(2‐vinylnaphthalene) into poly[bis(4‐phenyl)(2,4,6‐trimethylphenyl)amine] as the hole transport layer with improved ion‐blocking capability. Consequently, this layer effectively reduces defect concentration, suppresses ion migration, and modulates energy level alignment, leading to an impressive efficiency exceeding 23% for doctor‐bladed FAPbI3 PSCs. Moreover, the corresponding unencapsulated devices demonstrate remarkable durability, maintaining over 80% of their initial value after undergoing rigorous stress tests in accordance with the International Electrotechnical Commission 61215 standard for temperature, humidity, and illumination. These tests include 1000 h of thermal cycling and a long‐term operational test lasting 600 h under maximum power point tracking.

Bridging the buried interface with conjugated molecule for highly efficient carbon-based inorganic CsPbI2Br perovskite solar cells fabricated in air

Manipulating the buried interface of all-inorganic perovskite solar cells (PSCs) is essential to improve the performance of devices. However, the conventional modifiers of interface typically present insulating feature that can impede the transportation of carrier, leading to an inferior charge transport efficiency. Herein, we propose a conjugated molecule, 2,4-hexadienoic acid potassium salt, which can act as a bridge at the buried interface of device and improve the crystallization of perovskite film. Besides, this interfacial modifier also promotes larger and denser grains, passivating defects and suppress non-radiative recombination of buried interface. Simultaneously, the electrical performance of tin oxide film is enhanced and facilitate a better energy level alignment. Consequently, carbon electrodes-based PSCs (C-PSCs) are fabricated via a hot air-assisted method in air, and C-PSCs based on all-inorganic perovskite demonstrate significant enhancement of open circuit voltage (1.25 V) via conjugated molecule modification, and the power conversion efficiency (PCE) increase significantly from 10.86 % to 13.11 %. Moreover, unencapsulated target devices exhibit better stability than the control devices. This work offers a new idea to construct an interfacial bridge via conjugated molecule for efficient and stable C-PSCs fabricated in air.