以昇陳

Multiple functional layers are stabilized by the simultaneous suppression of the migration of multiple mobile chemical species based on host–guest interaction via calixarene supramolecules (C8A). The C8A-doped regular devices based on the two-step perovskite deposition method achieve a PCE of 26.01% (certified 25.68%). The C8A-modified p-i-n inverted PSCs obtain a champion PCE of 27.18% (certified 26.79%). The resulting unsealed inverted device retains 95% of its initial PCE after 1015 h of continuous operation at maximum power point.

Abstract

The migration of multiple chemical species is are main factor leading to the intrinsic instability of perovskite solar cells (PSCs). Herein, a universal ion migration suppression strategy is innovatively reported to stabilize multiple functional layers by simultaneously suppressing the migration of multiple mobile chemical species based on host–guest interaction via calixarene supramolecules. After incorporating 4-tert-butylcalix[8]arene (C8A), the interfacial defects are passivated, suppressing trap-assisted nonradiative recombination. Moreover, the p-doping of Spiro-OMeTAD is facilitated, and the extraction and transport of holes are promoted for n-i-p regular PSCs. The C8A doped regular devices based on the two-step perovskite deposition method achieve a power conversion efficiency (PCE) of 26.01% (certified 25.68%), which is the record PCE ever reported for the TiO₂-based planar PSCs. The C8A passivated p-i-n inverted PSCs obtain a champion PCE of 27.18% (certified 26.79%), which is the highest PCE for the PSCs using the vacuum flash evaporation method. The resulting unsealed inverted device retains 95% of its initial PCE after 1015 h of continuous operation at maximum power point. This work provides a feasible and effective avenue to address the intrinsic instability of perovskite-based photovoltaics and other optoelectronic devices.

Nature Photonics, Published online: 21 May 2025; doi:10.1038/s41566-025-01684-3

Nature Photonics, Published online: 26 May 2025; doi:10.1038/s41566-025-01675-4

A clear CsPbBr₃-CsPbI₃ nanocrystal film interface is fabricated through transfer printing to decouple the influence of ion migration inside a single nanocrystal or across nanocrystals along the electric field on the performance of PeLEDs. Halogen ions crossing the nanocrystal film interface cause phase separation and poor device stability, while confined halogen ions in a single nanocrystal negligibly influence the spectral stability.

Abstract

Mixed-halide perovskite light-emitting diodes (PeLEDs) face the critical challenge of field-dependent phase separation. Discrete colloidal CsPbX₃ nanocrystals anchored with ligands are promising to suppress phase separation, yet it remains a mystery how ion migration proceeds when integrated into LEDs as emissive films. Specifically, the influence of ion migration inside a single nanocrystal or across the nanocrystals along the electric field on the performance of PeLEDs needs to be decoupled. Here, a low-temperature-assisted transfer-printing method is developed to construct a model PeLED containing a clear CsPbBr₃-CsPbI₃ nanocrystal film interface for tracing the ion migration between perovskite nanocrystal films along the direction of electric fields. The comprehensive study demonstrates that halogen ions crossing the nanocrystal film interface lead to severe phase separation and poor device stability, rather than the horizontal intra-layer diffusion. The monolayer CsPbX₃ nanocrystal film prevents the field-dependent phase separation caused by interlayer ion migration, significantly improving electroluminescent stability, including spectrum and lifetime. The optimized structure achieves a high external quantum efficiency of 26.9% and a remarkably improved operational half-lifetime of 61.2 h at an initial luminance of 100 cd m⁻² in pure-red PeLEDs based on mixed-halide CsPb(I_x/Br_1-x)₃, more than 300 times longer than the control device using multilayer nanocrystals.

A synergistic interface engineering strategy is introduced that combines a co-assembled monolayer with in situ polymerization to optimize the buried interface of perovskite film. The polymerized layer at the interface enhances interfacial adhesion, regulates perovskite crystallization, and reinforces structural integrity by strongly anchoring organic cations through multiple hydrogen bonds.

Abstract

The strategic utilization of self-assembled monolayers (SAMs) significantly advances the interfacial contact and power conversion efficiency (PCE) of inverted perovskite solar cells (IPSCs). However, inadequate adhesion between the SAM and perovskite layer remains a critical challenge, limiting further performance enhancement. Herein, a synergistic interface engineering strategy is introduced that combines a co-assembly approach with in situ polymerization to optimize the buried interface of perovskite film. Specifically, 11-Mercaptoundecylphosphoric acid (MPA) is incorporated into a SAM to form co-SAMs, improving homogeneity and mitigating defects at the NiO _x surface. Simultaneously, the ionic liquid (IL) monomer 1-Allyl-3-vinylimidazolium bis((trifluoromethyl)sulfonyl) imide (AVMTF₂) is incorporated into the perovskite precursor. The aggregation of ILs cation at the bottom interface facilitates in situ polymerization via sulfhydryl end groups, forming the POL-AVM polymer at the perovskite/SAM interface. This polymer enhances interfacial adhesion, regulates perovskite crystallization, and reinforces structural integrity by strongly anchoring organic cations through multiple hydrogen bonds. As a result, this synergistic strategy achieves a champion PCE of 26.25% (certified 26.04%), along with excellent long-term stability, retaining 95.6% of its initial efficiency after 1000 h of continuous operation under the ISOS-L-2I protocol.

2D/3D heterostructures have significantly advanced the performance of perovskite solar cells (PSCs), but their long-term photostability at elevated temperatures remains a major challenge. This study introduces amidinium-based 2D spacer cations with high pKa values to improve both the photostability and efficiency of PSCs. Unlike traditional ammonium-based passivators, amidinium cations effectively prevent detrimental deprotonation reactions that occur at high temperatures, ensuring a stable interface between 2D and 3D perovskite phases. As a result, PSCs with amidinium passivation retain 90.6% of their initial efficiency after 1000 h of operation at 85 °C. Furthermore, amidinium-based 2D perovskite films provide excellent bulk and surface passivation effects, enabling the highest PCE of 26.52% among all reported 2D/3D PSC devices. These findings offer a promising route toward developing more durable and efficient PSCs.

Abstract

2D/3D perovskite heterojunctions represent a promising approach to enhance the efficiency and stability of perovskite solar cells (PSCs). However, the photostability at elevated temperatures of conventional 2D/3D heterostructures, employing ammonium-based spacer cations, is severely limited by deprotonation reactions, hindering their practical application. In this study, amidinium-based 2D spacer cations as an alternative, leveraging their higher acid dissociation constants, to mitigate deprotonation-induced instability while providing excellent defect passivation effect is introduced. Amidinium passivation not only facilitates formation of thermally stable 2D/3D heterostructures but also suppresses non-radiative recombination and enhances carrier transport dynamics. PSCs with amidinium-based bulk and surface passivation achieve a state-of-the-art power conversion efficiency of 26.52% for 2D/3D PSCs and exhibit outstanding high-temperature photostability, retaining 90.6% of initial efficiency after 1000 h of continuous illumination at maximum power point at 85 °C. This work offers valuable insights into designing high-performance, durable PSCs under challenging conditions.

A π-extended, heavy-atom design enables multi-resonance thermally activated delayed fluorescence emitters with an ultrafast reverse intersystem crossing rate of 3.0 × 10⁶ s⁻¹ while preserving narrowband emission in the deep-blue region. The best-performing device achieves an emission maximum at 456 nm, a full-width at half-maximum of 18 nm, a record-high external quantum efficiency of 40.5%, and a Blue Index of 422, charting a promising route toward next-generation deep-blue display technologies.

Abstract

Multi-resonance thermally activated delayed fluorescence (MR-TADF) emitters hold great promise for high-resolution OLEDs, yet achieving both ultranarrow emission and efficient triplet utilization in the deep-blue region remains challenging. Here, a synergistic molecular design is reported that combines π-extension and heavy-atom incorporation to effectively reconcile the trade-off between color purity and fast reverse intersystem crossing (RISC). In this approach, π-extension narrows the emission bandwidth and reduces the singlet–triplet energy gap, while the strategic introduction of chalcogen atoms selectively enhances spin–orbit coupling with minimal impact on the emission spectrum. As a result, the new emitter exhibits a peak emission at 453 nm with an exceptionally narrow full width at half maximum (FWHM) of 17 nm and a high RISC rate constant of 3.0 × 10⁶ s⁻¹. When incorporated into a non-sensitized OLED, the emitter meets the European Broadcast Union (EBU) deep-blue standard with CIE coordinates as low as (0.140, 0.059), and sustains a brightness exceeding 30,000 cd m⁻². Notably, the device achieves a record-high external quantum efficiency (EQE_max) of 40.5% with minimal roll-off—retaining 38.4% and 28.2% at 100 and 1,000 cd m⁻², respectively—and attains a Blue Index (BI) of 422 cd A⁻¹ CIE_y ⁻¹. These findings highlight the effectiveness of our tactic in overcoming prior limitations where heavy-atom doping often compromises color purity, paving the way for next-generation emitters in advanced display and lighting applications.

The perovskite-substrate interfaces are reinforced by using a dual-sided anchoring polymeric hole transporter, which enables significantly enhanced interfacial adhesion and defect passivation. The resulting inverted structured perovskite solar cells achieve 26.8% efficiency with excellent operational stability at 85 °C. This work demonstrates the critical role of interfacial stabilization for high-performance and stable perovskite solar cells.

Abstract

Interfacial reliability is critical for the long-term stability of perovskite solar cells (PSCs), yet the perovskite-substrate interface represents the most vulnerable part in high-efficiency devices. Here, this interface, by incorporating a dual-sided anchoring polymeric hole-transporting interlayer is reinforced with abundant coordinating pyridyl units as side chains, which induces strong adhesion between the perovskite and substrate by forming multidimensional interactions with adjacent layers. This simultaneously enhances the mechanical strength through effective distribution and dissipation of mechanical stress and the electronic quality of the perovskite-substrate interface through defect passivation. The resulting PSCs exhibit a high power conversion efficiency (PCE) of 26.8% (certified at 26.6%). With a more robust perovskite composition, devices maintain 98% of their initial PCE of ≈26% after maximum-power-point tracking at 85 °C for 1500 h. These devices exhibit excellent fatigue resistance under thermal cycling (-40 to 85 °C), retaining 93% efficiency after undergoing 900 cycles.

This work investigates the effects of ascorbic acid (AA) treatment on CsPbBrI₂ nanocrystals using computational and spectroscopic techniques. Effective surface trap passivation by AA enhances photoluminescence, suppresses photoluminescence blinking, and minimizes phase segregation under both light and electrical bias. AA-treated CsPbBrI₂ exhibits long-term stability and exceptional electrocatalytic performance, providing a straightforward route to phase-stable mixed-halide perovskite nanocrystals for various applications.

Abstract

Mixed-halide CsPbBrI₂ perovskite nanocrystals (PNC) exhibit defect tolerance and a low bandgap, making them promising for optoelectronic, photovoltaic, and catalytic applications. However, their performance is hindered by phase instability under light exposure and electrical bias, driven by iodine expulsion, which disrupts charge transport and is further exacerbated by trap-mediated intense photoluminescence (PL) blinking. This study investigates the nature of these trap states and their role in carrier recombination through ensemble- and single-particle-level analyses. These findings highlight the critical role of passivating ligands in stabilizing PNCs, identifying ascorbic acid (AA) as an optimal surface passivation due to its multidentate binding capability, as further supported by DFT calculations. Trion blinking in untreated PNCs indicates the presence of long-lived trap states, whereas AA-treated PNCs, which retain only shallow traps near the band edges, exhibit exclusively band-edge carrier (BC) blinking. AA-treated PNCs double the ON fraction in PL trajectories and remain stable for over 90 days in ambient conditions. By effectively passivating deep traps, AA treatment suppresses charge carrier trapping, mitigates phase segregation, and enhances charge transport. Leveraging these improvements, AA-treated CsPbBrI₂ PNCs are employed for the first time as electro/photoelectro-catalysts in the reduction of 4-nitrophenol, exhibiting exceptional performance.

Cooling down the thermally-annealed perovskite film in air ambiance with controlled humidity endows the resultant film with modified surface morphology, enhanced radiative combination, and reduced lattice strain, as well as an amplified passivation effect based on the PEAI molecule. The above positive effects contribute to a high efficiency of 25.2% for the resultant perovskite solar cell.

Abstract

Defect density on the perovskite film surface significantly exceeds that found in the bulk, primarily due to the presence of dangling bonds and excessive strain. Herein, a synergistic surface engineering is reported aimed at reducing surface defects of perovskite films. This method involves subjecting the thermally-annealed perovskite films to a controlled cooling condition involving an ambient environment with regulated humidity, as opposed to a nitrogen environment, followed by phenethylammonium iodide (PEAI) passivation. The perovskite films treated with moisture cooling (MC) exhibit enhanced radiative recombination, prolonged charge carrier lifetime, and improved hole transport and extraction when in contact with the hole transport layer (HTL), alongside a significant reduction in strain. Notably, the passivation effect of PEAI on the MC-treated perovskite films is significantly amplified compared with the films subjected to nitrogen cooling (NC) treatment, as evidenced by a more uniform surface potential mapping and a markedly extended charge carrier lifetime. This enhanced passivation effect may arise from the higher ratio of newly-formed 2D perovskite phase PEA₂FAPb₂I₇ to PEA₂PbI₄ in the MC-treated film. Consequently, the MC-based perovskite solar cell (PSC) achieves a champion power conversion efficiency (PCE) of 25.28%, surpassing that of the NC-treated device, which exhibits a PCE of only 24.01%.

An co-adsorbent 4-phosphoricbutyl ammonium iodide (4PBAI) is used to improve the performance of 4-(7H-dibenzo[c,g]carbazole-7-yl) phosphonic acid (4PADCB) in self-assembled molecules (SAM) based hole-selective contact. The 4PBAI successfully enhanced the homogeneity of the film, increased conductivity, and exhibited strong interaction with the perovskite layer and defects, leading to a perovskite solar cell device with power conversion efficiency of 24.96%.

Abstract

The inverted perovskite solar cells based on hole-selective self-assembled molecules (SAMs) have been setting new efficiency benchmarks. However, the agglomeration of SAM and lack of defect passivation ability are two critical issues that need to be addressed. It is demonstrated that by blending co-adsorbent 4-phosphoricbutyl ammonium iodide (4PBAI) with 4-(7H-dibenzo[c,g]carbazole-7-yl) phosphonic acid (4PADCB), enhanced homogeneity, conductivity, and better energy levels can be realized for the co-SAM hole-selective contact. The ammonium functional group on 4PBAI also can effectively passivate the defects at the buried interface and template high-quality perovskite growth. Assisted by synergistic top interface modification, the power conversion efficiency of the optimized device reaches 24.96%, which can retain 95% of the initial after 1200 h in ambient for the unencapsulated device. The findings suggest that a well-designed co-adsorbent can effectively address the limitations and further enhance the performance of cutting-edge SAMs.

A formamidinium-based in-situ coordination (F-ISS) strategy is proposed to optimize the buried interface in n-i-p perovskite solar cells (PSCs), effectively improving electron transport layer (ETL) uniformity. This strategy achieves device performance with an efficiency of 25.61% for small-area devices and 21.72% for 18.55 cm² mini-modules, while boosting stability by retaining 80% of initial efficiency after 1000 hours of continuous illumination.

Abstract

Defects at the buried interface and interfacial energy misalignment are critical challenges in perovskite solar cells (PSCs), causing severe carrier nonradiative recombination and introducing degradation centers that limit the device performance. In particular, issues such as void formation, poor adhesion, and interfacial defects at the buried interface compromise both efficiency and durability of PSCs. To address these challenges, a formamidinium-based in situ coordination (F-ISS) strategy is proposed to optimize the buried interface in normal-structure PSCs. By incorporating various formamidinium-based materials (FAI, FABr, and FACl), the F-ISS approach effectively reduces interfacial defects, mitigates nanoparticle aggregation, enhances the electrical and morphological uniformity of electron transport layer (ETL), and improves energy level alignment. The F-ISS-incorporation ETL exhibits improved surface smoothness, reduced trap density, and stronger interfacial adhesion, leading to superior quality of buried interface. These enhancements result in superior device performance, with normal-structure device achieving an efficiency of 25.61%, surpassing control device with efficiency of 23.43%. Additionally, the PCE of a mini-module with an active area of 18.55 cm² achieved 21.72%, surpassing control device with efficiency of 19.76%. Moreover, the F-ISS strategy significantly boosts device stability, retaining over 80% of the initial efficiency after 1000 h of continuous illumination at maximum power point testing. These findings establish the F-ISS strategy as a promising solution for addressing the inherent challenges of the buried interface in perovskite photovoltaics.

In this work, a novel thiazole derivative, 1,3-thiazole-2-carboximidamide (TZC) is introduced in 3D perovskite to form 1D TZCPbI3 perovskite, which acts as crystal seeds to regulate crystallization kinetics and eventually construct 1D/3D mixed-dimensional perovskite film with n-type doping characteristics. The photovoltaic performance of PSCs is significantly improved.

Abstract

Developing low-dimensional perovskites to enhance both single-junction and tandem solar cells is of great interest for improving photovoltaic performance and durability. Herein, a novel 1D perovskite based on 1,3-thiazole-2-carboximidamide (TZC) cation is introduced, which exhibits robust chemical interactions with PbI₂ and 3D perovskite, enabling the fabrication of high-quality mixed-dimensional perovskite films identified by both HR-TEM and GIWAXS analyses. Benefiting from the lower formation energy barrier of 1D perovskites, they can preferentially form and act as crystal seeds to regulate perovskite crystallization kinetics with optimized morphology and improved crystallinity. In addition to effectively passivating surface defects and suppressing nonradiative recombination, TZC-enabled 1D perovskites exhibit pronounced n-type doping characteristics, leading to an elevated Fermi level (from −4.63 to −4.44 eV) and facilitating improved charge carrier extraction and transport in p-i-n perovskite devices. As a result, this strategy not only significantly enhances the power conversion efficiency (PCE) of the widely studied 1.55 eV bandgap perovskite but also boosts the PCE of 1.68 and 1.85 eV wide-bandgap perovskite devices, achieving outstanding PCEs of 22.52% and 18.65%, respectively. These findings highlight the immense potential of TZC-functionalized 1D perovskites for enhancing both high-performance single-junction perovskite and tandem solar cell applications.

The degradation of perovskite precursors is suppressed by modulating the position and type of functional groups in stabilizers. 4-hydrazinobenzenesulfonic acid (4-HBSA), with the lowest pK _a, effectively improved stability, passivated grain boundary defects, and increased carrier lifetime, leading to a maximum PCE of 26.79% in inverted PSCs fabricated by vacuum flash technology under ambient conditions.

Abstract

The instability of perovskite precursor solution induced by deprotonation of organic cations and oxidation of iodide ions substantially deteriorates the reproducibility and reliability of the photovoltaic performance of perovskite solar cells (PSCs). The above decomposition reactions can be conquered via the synergistic engineering of organic functional groups. However, how spatial conformation and type of weak acid functional groups impact the stability of perovskite precursor solution remains to be investigated. Herein, it is uncovered that the position of functional groups on the benzene and the type of weak acid functional groups remarkably influence the acid dissociation constant (pK _a) and thus the stability of perovskite inks. The pK _a plays a decisive role in suppressing the deprotonation of organic cations and following the amine-cation addition-elimination reaction. The 4-hydrazinobenzenesulfonic acid (4-HBSA) with the lowest pK _a is optimal in stabilizing perovskite inks and mitigating nonradiative recombination through defect passivation. This breakthrough enables the inverted PSCs to deliver a power conversion efficiency (PCE) of 26.79% (certified 26.36%, the highest PCE value for PSCs prepared in ambient conditions) using vacuum flash evaporation technology. The modulated PSC could maintain 92% of its initial efficiency after 2000 h of continuous maximum power point tracking.

This work reports Rec. 2020 compliant pure-green mixed-cation perovskite light-emitting diodes, presenting a champion EQE of 31.89%, average EQE of 29.5%, maximum luminance of 2 × 10⁵ cd m⁻² and half-lifetime of ≈3500 h at an initial luminance of 100 cd m⁻². The results are enabled by synergistic co-additives, which can manipulate nanograin crystallization and mitigate crystal defects effectively.

Abstract

Perovskite light-emitting diodes (PeLEDs) compliant with Rec. 2020 standards have raised increasing attention for next-generation displays. As a class of pure-green emitters, the mixed-cation FA_xCs_1-xPbBr₃ perovskites exhibit compatible band emission, but suffer from inferior luminescence performance. The approach to tackling this issue is hindered by a lack of in-depth understanding of their crystallization manipulating mechanism. This work unveils the crystallization process of mixed-cation FA_0.7Cs_0.45GA_0.1PbBr₃ perovskites, demonstrating the fast spontaneous growth readily induces severe crystal defects accompanied by poor charge confinement. This motivates us to introduce additional kinetic barriers to manipulate the perovskite crystallization via the synergistic co-additives of 3-((2-(methacryloyloxy)ethyldimethyl)ammonio)-propane-1-sulfonate (DMAPS) and 1,4,7,10,13,16-hexaoxacyclooctadecane (crown). The multifunctional groups in the co-additives afford robust chemical affinities with the diverse organic and inorganic precursor ions simultaneously, which enable decent nanograin growth with effective crystal defect healing and charge confinement. Ultimately, mixed-cation FA_0.7Cs_0.45GA_0.1PbBr₃ perovskites with a high photoluminescence quantum yield of 96% are achieved. The resultant pure-green PeLEDs with the Rec. 2020 compliance exhibit a champion external quantum efficiency (EQE) of 31.89%, average EQE of 29.5%, maximum luminance of 2 × 10⁵ cd m⁻² and operational half-lifetime of 3.2 h at an initial luminance of 7000 cd m⁻² (extrapolated: ≈3500 h at 100 cd m⁻²).

This study proposes a discrete supramolecular dimerization strategy for achieving efficient chiral multi-resonance thermally activated delayed fluorescence emitters featuring aggregation-induced circularly polarized luminescence enhancement. The resulting electroluminescence devices achieve narrowband emission with full width at half maximum down to 26 nm and a record-breaking figure of merit (|g _EL| × EQE) of 4.12 × 10⁻³.

Abstract

Achieving narrowband emission, high efficiency, and circularly polarized luminescence (CPL) in organic light-emitting diodes (OLEDs) remains a significant challenge. In this study, a discrete supramolecular dimerization strategy is presented to overcome this limitation. By incorporating a helical arylamine with a sterically demanding configuration into a multi-resonance narrowband emitter, the formation of a unique dimeric structure in the solid state is enabled. Unlike conventional multi-resonance emitters prone to aggregation-caused quenching and continuous stacking, the CPL emitters form discrete, well-separated dimers. This distinct supramolecular arrangement not only preserves high photoluminescence quantum yield and narrowband emission but also amplifies CPL signals by optimizing intermolecular electronic coupling. OLEDs incorporating these enantiomers at a 10 wt.% doping level exhibit outstanding performances, including a narrow full-width at half-maximum of 30 nm, maximum external quantum efficiencies (EQE) of 33.5% and 32.4%, and impressive electroluminescence dissymmetry factors (g _EL) of +8.7 × 10⁻³ and −9.1 × 10⁻³, respectively. Remarkably, increasing the doping concentration to 20 wt.% further boosts the g _EL values to +1.6 × 10⁻² and −1.8 × 10⁻². This enhancement leads to Figures of Merit (EQE × |g _EL|) of 3.71 × 10⁻³ and 4.12 × 10⁻³, among the highest values for CPL devices.

Here this study discovers that hole accumulation is an inevitable reason for Sn²⁺ oxidation in Sn-Pb perovskite solar cells (PSCs). Basing on this, a non-planar hole transport layer of P3CT/Me-4PACz is designed. P3CT/Me-4PACz will form non-planar films with spikes penetrating perovskite bulk, inhibiting holes accumulation. Resulted PSCs exhibit >24% efficiency with good stability, retaining 82% of initial efficiency after MPP tracking for 1000 h.

Abstract

Sn-Pb perovskite solar cells (PSCs) own the highest theoretical efficiency due to their ideal bandgap. However, the efficiency of Sn-Pb PSCs remains 22–23% at present, which is much lower than Pb-based PSCs. One key reason lies in the Sn²⁺ oxidation issue. Here, this study demonstrates that apart from well-known chemical environmental oxidation, photo-generated holes and their accumulation are also a critical factor for Sn²⁺ oxidation in Sn-Pb PSCs. To address this issue, a non-planar hole transport layer (HTL) of P3CT/Me-4PACz is designed through solution micelle regulation. P3CT/Me-4PACz will form a 3D HTL film with a spike-like structure penetrating Sn-Pb perovskite bulk to accelerate hole extraction, thus inhibiting holes accumulation and Sn²⁺ oxidation. Resulted Sn-Pb PSCs exhibit the highest efficiency of over 24% with good operational stability, retaining 82% of initial efficiency after continuous MPP tracking for 1000 h at an elevated temperature of 55 °C.

A hydrazinelinked covalent organic framework (COF) is synthesized for the first time and integrated into perovskite for multidimensional regulation of crystallization, defect states, and charge separation, synergistically. Benefiting from the oriented crystallization, which eliminates defects, together with the optimized interfacial charge transfer, the optimal device achieves an excellent efficiency of 26.21% with greatly improved humidity, thermal, and illumination stabilities.

Abstract

Despite the remarkable advancements in inverted perovskite solar cells, their commercialization remains hindered by critical bottlenecks in efficiency and stability stemming from inadequate crystallization and unfavorable interfacial states. Herein, for the first time, a judiciously designed hydrazine-linked covalent organic framework (COF) with long alkane phosphate branch chains, named 12-SD-COF, is synthesized and integrated into the perovskite precursor to achieve multidimensional regulation of crystallization, defect states, and charge separation synergistically. It is found that the 12-SD-COF featuring periodic pores, large planar structure, and abundant binding groups is extruded from the precursor solution onto the buried interface, surface, and grain boundaries, facilitating oriented crystallization while eliminating defects of perovskites, thereby yielding high-quality crystals with suppressed non-radiative recombination. Simultaneously, the interfacial charge separation is synergistically facilitated by the p-type doping-optimized energy level alignment and the induced intramolecular electric field, ultimately achieving an exceptional power conversion efficiency (PCE) of 26.21%, the highest yet reported for COF-modified. Impressively, the non-encapsulated resultant device delivers greatly improved stabilities, with maintaining over 92% of initial PCE after being aged under 85 °C continuous heating stress for 800 h, 1000 h in 50±3% relative humidity air, and 1200 h under continuous 1-sun illumination, respectively.

A new class of luminescent organic quantum materials is introduced, formed by attaching a stable radical to TADF chromophores. Due to ferromagnetic exchange coupling, a high-spin quartet state forms upon excitation, which can thermally access a bright state. ≈200 nm tunability of the emission color is reported, and coherent spin manipulations with microwaves are achieved.

Abstract

High-spin states in organic molecules offer promising tuneability for quantum technologies. Photogenerated quartet excitons are an extensively studied platform, but their applications are limited by the absence of optical read-out via luminescence. Here, a new class of synthetically accessible molecules with quartet-derived luminescence is demonstrated, formed by appending a non-luminescent TEMPO radical to thermally activated delayed fluorescence (TADF) chromophores previously used in OLEDs. The low singlet-triplet energy gap of the chromophore opens a luminescence channel from radical-triplet coupled states. A set of design rules is established by tuning the energetics in a series of compounds based on a naphthalimide (NAI) core. Generation of quartet states is observed and the strength of radical-triplet exchange is measured. In DMAC-TEMPO, up to 72% of detected photons emerge after reverse intersystem crossing from the quartet state repopulates the state with singlet character. This design strategy does not rely on a luminescent radical to provide an emission pathway from the high-spin state. The large library of TADF chromophores promises a greater pallet of achievable emission colours.