JIALINGBO

Fast synthesis of α-phase crystallized mixed-cation perovskite powder assisted with moisture in ambient air is developed. The significant role of moisture in introducing the solvation effect and the facet orientation change of PbI₂ is demonstrated by a combined experimental and theoretical investigation. Perovskite solar cells based on α-phase mixed-cation perovskite powder deliver an impressive PCE of 24.07 %.

Abstract

Phase-pure crystallised perovskite is considered an excellent precursor for fabricating high-stability perovskite films with minimal defects. However, currently available protocols for synthesising crystallised perovskites must be conducted in an inert atmosphere or in the presence of an organic solvent as the reaction medium, which hinders mass production. Here, we report the fast synthesis of α-phase-crystallised perovskite powder assisted by moisture in ambient air. Moisture can promote the reaction between PbI₂ and organic salts and facilitate complete phase transition, as demonstrated in a joint experimental and theoretical study. Perovskite solar cells with a power conversion efficiency of 24.07 % were achieved using phase-pure crystallised perovskite powder as the precursor. This ambient-air-compatible method opens new vistas to reproducible high-quality precursors for large-scale photovoltaic applications.

An ultrathin hybrid hole transporting layer employing NiO_x/[2-(9H-carbazol-9-yl) ethyl]phosphonic acid enables complete and uniform coverage on fully textured indium tin oxide (ITO)/silicon surface with pyramid structures of 2–5 µm sizes. As a result of the depleted shunt pathways between ITO and perovskite top cell, a certified record efficiency—28.84%—is achieved on perovskite/silicon tandem solar cells with fully textured, production-line compatible bottom silicon wafers.

Abstract

Perovskite/silicon tandem solar cells are promising avenues for achieving high-performance photovoltaics with low costs. However, the highest certified efficiency of perovskite/silicon tandem devices based on economically matured silicon heterojunction technology (SHJ) with fully textured wafer is only 25.2% due to incompatibility between the limitation of fabrication technology which is not compatible with the production-line silicon wafer. Here, a molecular-level nanotechnology is developed by designing NiO_x/2PACz ([2-(9H-carbazol-9-yl) ethyl]phosphonic acid) as an ultrathin hybrid hole transport layer (HTL) above indium tin oxide (ITO) recombination junction, to serve as a vital pivot for achieving a conformal deposition of high-quality perovskite layer on top. The NiO_x interlayer facilitates a uniform self-assembly of 2PACz molecules onto the fully textured surface, thus avoiding direct contact between ITO and perovskite top-cell for a minimal shunt loss. As a result of such interfacial engineering, the fully textured perovskite/silicon tandem cells obtain a certified efficiency of 28.84% on a 1.2-cm² masked area, which is the highest performance to date based on the fully textured, production-line compatible SHJ. This work advances commercially promising photovoltaics with high performance and low costs by adopting a meticulously designed HTL/perovskite interface.

The potentiality of interfaced structures between halide perovskites is predicated on the vast tunable space of perovskites, the ease with which to tailor perovskite semiconducting properties and the prospect to inject new functions. This article reviews recent advances on the perovskite–perovskite interfaced structures with a view to informing their rational design for optoelectronic devices.

Abstract

The tsunami of research on halide perovskites over the last decade is sparked by the unexpected revelation of their singular properties, creating a new field of perovskite optoelectronics with great achievements. Soon recognized is the importance of perovskite–perovskite (pe–pe) interfaced structures with coherent interfaces on account of the ease with which to tailor perovskite semiconducting properties, and the prospect to inject new functions and boost device performance. There have been prominent developments in the pe–pe interfaced structures concerning their innovative construction strategies, distinctive properties, and interesting optoelectronic applications. This article provides an overview of recent advances on the pe–pe interfaced structures with a view to informing their rational design and guiding the improvement of the derivate devices. It begins with introduction of the structures, energy levels, band alignments, and ion migration pertaining to the pe–pe interfaced structures. Next, five synthetic approaches are systematically presented. Then, theories, simulations, and characterizations of the interfaced structures are discussed. This is followed by highlighting the distinctive applications of the pe–pe interfaced structures in solar cells, detectors, and light-emitting diodes. Finally, the review is concluded by comprehensively summing up the key points covered and pointing out promising research directions along the line for future endeavors.

The preparation of perovskite solar cells by vacuum thermal evaporation processes has advantages in reproducibility, scalability, extendable applications, safety, and toxicity. In this review, materials and methods utilized for vacuum-processed perovskite solar cells are discussed, including precursor materials, the effect of the interlayer, and various deposition methods.

Perovskite solar cells (PSCs) based on inexpensive organic−inorganic hybrid semiconductors are considered a promising next-generation solar cell technology. For PSC commercialization, the further development of efficient and scalable fabrication methods is essential. To date, solution-based methods have been widely studied due to simplicity and cost-effectiveness. Despite the advantages, it is still necessary for developing vacuum-based methods as the alternative methods due to reproducibility and uniformity with in a large area. However, it is insufficiently studied for a systematic understanding of vacuum-based methods. To give helpful insight for understanding vacuum-based methods for PSC commercialization, this review introduces the precursor and charge transporting materials with the various preparation methods for vacuum-processed PSCs.

By simultaneous control of the intermediate phase during crystallization of the perovskite film and surface passivation using a single molecule additive N,N-dimethylimidodicarbonimidic diamide hydroiodide (DIAI), which has multiple functional groups, an impressive device photoelectric conversion efficiency as high as 24.13% with negligible hysteresis is obtained. The bare device without any encapsulation maintains 94.1% of its initial efficiency after ambient exposure for over 1000 h.

Abstract

With its power conversion efficiency surpassing those of all other thin-film solar cells only a few years after its invention, the perovskite solar cell has become a superstar. Controlling the intermediate phase of crystallization is a key to obtaining high-quality perovskite films. Herein, a single molecule additive, N,N-dimethylimidodicarbonimidic diamide hydroiodide (DIAI), is incorporated into the perovskite precursor to eliminate the influence of intermediate phases. By taking advantage of the interaction of DIAI and dimethyl sulfoxide (DMSO), the intermediate phase FAI-PbI₂-DMSO complex is eliminated, and δ-FAPbI₃ is entirely converted to the desired α-FAPbI₃ during the crystallization step, resulting in enlarged grain size and improved crystalline quality. This is the first observation in the solution method that FAPbI₃ can be obtained without an intermediate phase for high-performance perovskite solar cells. Furthermore, DIAI is effective at passivating surface defects, resulting in reduced defect density, increased carrier lifetime, and improved device efficiency and stability. The champion device achieves an efficiency of 24.13%. Furthermore, the bare device without any encapsulation maintains 94.1% of its initial efficiency after ambient exposure over 1000h. This work contributes a strategy of synergistic crystallization and passivation to directly form α-FAPbI₃ from the precursor solution without the influence of intermediate impurities for high-performance perovskite applications.

Nature, Published online: 01 September 2022; doi:10.1038/s41586-022-05268-x

Herein, a novel printed electrode deposition process is introduced to fabricate highly efficient, fully roll-to-roll coated perovskite solar cells. The dry press deposition method mitigates the risk of harmful solvent leaching and high temperature processing. Record device power conversion efficiencies of up to 16.7% are demonstrated for flexible, roll-to-roll coated perovskite solar cells with a vacuum-free electrode.

Abstract

Perovskite solar cells (PSCs) are attracting widespread attention due to their exceptional photovoltaic performance and their potential for large-scale production via low-cost, high-throughput roll-to-roll (R2R) methods. Full realization of this production approach requires replacement of the evaporated metal electrode commonly used in PSCs. Here, a novel vacuum-free R2R-compatible method is introduced to fabricate and deposit printed electrodes based on electrically conductive pastes, which avoids potential loss of PSC performance due to solvent migration from the pastes. Flexible R2R-fabricated PSCs with record power conversion efficiencies (PCEs) of up to 16.7% are produced by vacuum-free deposition of all functional layers, apart from the transparent conductive electrode. This performance compares very favorably with that of control flexible PSCs comprising an evaporated gold electrode, which displays PCEs of up to 17.4%. Furthermore, the PSCs comprising a printed electrode demonstrate outstanding operational and mechanical stability, with negligible loss of PCE after 24 h of continuous 1-sun illumination and retention of more than 90% of their initial PCE after 3000 cyclic bends.

CsPbI₂Br perovskite solar cells (PSCs) have received much attention because of the excellent thermal stability. In view of the existing problems of CsPbI₂Br PSCs, optimization methods including preparation process, additives, modification materials, carrier transport layers, application in tandem solar cells, and development of large area PSCs are summarized. Finally, the challenges and outlook of CsPbI₂Br PSCs are discussed.

Abstract

Over the past few years, all-inorganic perovskite solar cells (PSCs), especially CsPbI₂Br PSCs, have received much attention because of their excellent thermal stability and a suitable trade-off between light absorption and higher phase stability among the family of inorganic perovskites. In this progress report, the realization of highly efficient and stable CsPbI₂Br PSCs is summarized through preparation process, additive engineering, interface modification, and transport material selection. Furthermore, the application of CsPbI₂Br in tandem solar cells and its large-area development are highlighted. Finally, the challenges and outlook of CsPbI₂Br PSCs are discussed for further performance improvement and future practical deployment.

Highly-efficient green (λ_max = 515 nm) perovskite light-emitting diodes are developed by combining blends of the quasi-2D perovskite, PEA₂Cs₄Pb₅Br₁₆, and the wide bandgap organic semiconductor 2,7 dioctyl[1] benzothieno[3,2-b]benzothiophene, with different self-assembled monolayers as the hole-injecting interlayers.

Abstract

The high photoluminescence efficiency, color purity, extended gamut, and solution processability make low-dimensional hybrid perovskites attractive for light-emitting diode (PeLED) applications. However, controlling the microstructure of these materials to improve the device performance remains challenging. Here, the development of highly efficient green PeLEDs based on blends of the quasi-2D (q2D) perovskite, PEA₂Cs₄Pb₅Br₁₆, and the wide bandgap organic semiconductor 2,7 dioctyl[1] benzothieno[3,2-b]benzothiophene (C₈-BTBT) is reported. The presence of C₈-BTBT enables the formation of single-crystal-like q2D PEA₂Cs₄Pb₅Br₁₆ domains that are uniform and highly luminescent. Combining the PEA₂Cs₄Pb₅Br₁₆:C₈-BTBT with self-assembled monolayers (SAMs) as hole-injecting layers (HILs), yields green PeLEDs with greatly enhanced performance characteristics, including external quantum efficiency up to 18.6%, current efficiency up to 46.3 cd A⁻¹, the luminance of 45 276 cd m⁻², and improved operational stability compared to neat PeLEDs. The enhanced performance originates from multiple synergistic effects, including enhanced hole-injection enabled by the SAM HILs, the single crystal-like quality of the perovskite phase, and the reduced concentration of electronic defects. This work highlights perovskite:organic blends as promising systems for use in LEDs, while the use of SAM HILs creates new opportunities toward simpler and more stable PeLEDs.

This study first outlines the defect types and lists some recent research advances in defect passivation strategies and materials for perovskite, surface, grain boundary and charge transport layer interfaces, respectively. Based on this, it further summarizes the deficiencies and perspectives in the development of passivation strategies for all-inorganic halide perovskite solar cells.

Abstract

All-inorganic halide perovskite materials have attracted increasing attentions in recent years due to their superior stability and adjustable band gap which make them very suitable for the top cells of multi-junction solar cells. Nonetheless, the power conversion efficiency of all-inorganic halide perovskite solar cells is still far from satisfaction. The widespread use of the conventional solution method in the preparation process causes many different defects and carrier transport barriers at the grain boundaries and interfaces of the perovskite films, which can cause severe hysteresis behavior and non-radiative recombination, resulting in low efficiency and hindering their rapid commercialization. While, the selection of suitable passivation materials and techniques can have the most significant potential in reducing the defect recombination centers between the bulk perovskite, the film surface and grain boundaries, and the interface between the various communities (perovskite/electron transport layer [ETL], perovskite/hole transport layer [HTL]). Herein, this study reviews the current research process on various passivation strategies developed for all-inorganic halide perovskite solar cells, especially for the defects in the perovskite surface, and grain boundaries, perovskite/HTL interface and perovskite/ETL interface. Finally, the authors look ahead to the prospects and challenges of exploring defect passivation in all-inorganic halide perovskite solar cells.

Hot casting is shown to allow for reduced loading of dimethyl sulfoxide (DMSO) in perovskite precursor inks, and remnant DMSO in films. This suppresses formation of undesired byproducts. The resulting perovskite layers show fewer defects, while their solar cells exhibit superior operational stability under considerable UV-containing simulated solar exposure over 3000 h.

Abstract

High-performance inorganic–organic lead halide perovskite solar cells (PSCs) are often fabricated with a liquid additive such as dimethyl sulfoxide (DMSO), which retards crystallization and reduces roughness and pinholes in the perovskite layers. However, DMSO can be trapped during perovskite film formation and induce voids and undesired reaction byproducts upon later processing steps. Here, it is shown that the amount of residual DMSO can be reduced in as-spin-coated films significantly through use of preheated substrates, or a so-called hot-casting method. Hot casting increases the perovskite film thickness given the same concentration of solutions, which allows for reducing the perovskite solution concentration. By reducing the amount of DMSO in proportion to the concentration of perovskite precursors and using hot casting, it is possible to fabricate perovskite layers with improved perovskite–substrate interfaces by suppressing the formation of byproducts, which increase trap density and accelerate degradation of the perovskite layers. The best-performing PSCs exhibit a power conversion efficiency (PCE) of 23.4% (23.0% stabilized efficiency) under simulated solar illumination. Furthermore, encapsulated devices show considerably reduced post-burn-in decay, retaining 75% and 90% of their initial and post-burn-in efficiencies after 3000 h of operation with maximum power point tracking (MPPT) under high power of ultraviolet (UV)-containing continuous light exposure.

Publication date: October 2022

Source: Nano Energy, Volume 101

Author(s): Ali Hassan, Zhijie Wang, Yeong Hwan Ahn, Muhammad Azam, Abbas Ahmad Khan, Umar Farooq, Muhammad Zubair, Yu Cao

High-performance inverted perovskite solar cells are fabricated with KBF₄ additive in perovskite layers. The introduction of KBF₄ can enlarge grain size, manipulate microstrain, and suppress the formation of deep trap states in the perovskite layers. The synergistic effects greatly elongate carrier lifetime and enable power conversion efficiencies over 23% and 21% for rigid and flexible devices.

Abstract

Triple-cation mixed perovskites have attracted much attention recently owing to their prominent optoelectronic properties and good stability for perovskite solar cells. However, the introduction of those cations with different sizes in the perovskite materials will drive the perovskite lattice away from ideal cubic structure and lead to microstrain in the resultant films. Herein,a small amount of KBF₄ as an additive to elevate the quality of triple-cation mixed perovskite thin films is introduced. It is found that KBF₄ can enhance the crystallinity and alleviate microstrain of the perovskite thin films. Moreover, KBF₄ can passivate defects in perovskite grains, leading to much longer carrier lifetimes. Consequently, the resultant devices show improved fill factor, enhanced device efficiency, and better device stability. Under optimum fabrication conditions, triple-cation mixed perovskite solar cells with an inverted structure show power conversion efficiency over 23% as well as excellent stability under different conditions.

Field effect passivation is identified as the origin of the voltage enhancement upon inserting a LiF interlayer at the electron selective contact of perovskite solar cells by high sensitivity near-UV photoelectron spectroscopy. LiF increases the defect density in the C₆₀, however, the minority charge carrier density in the vicinity of the interface is lowered, resulting in an overall reduction in the non-radiative recombination.

Abstract

The fullerene C₆₀ is commonly applied as the electron transport layer in high-efficiency metal halide perovskite solar cells and has been found to limit their open circuit voltage. Through ultra-sensitive near-UV photoelectron spectroscopy in constant final state mode (CFSYS), with an unusually high probing depth of 5–10 nm, the perovskite/C₆₀ interface energetics and defect formation is investigated. It is demonstrated how to consistently determine the energy level alignment by CFSYS and avoid misinterpretations by accounting for the measurement-induced surface photovoltage in photoactive layer stacks. The energetic offset between the perovskite valence band maximum and the C₆₀ HOMO-edge is directly determined to be 0.55 eV. Furthermore, the voltage enhancement upon the incorporation of a LiF interlayer at the interface can be attributed to originate from a mild dipole effect and probably the presence of fixed charges, both reducing the hole concentration in the vicinity of the perovskite/C₆₀ interface. This yields a field effect passivation, which overcompensates the observed enhanced defect density in the first monolayers of C₆₀.

Novel electron-accepting material, PDI–Cb, is synthesized by introducing diphenyl-o-carboranyl groups at the bay positions of the PDI unit and its photophysical and electrochemical properties are systematically investigated. The inverted perovskite solar cells with PDI–Cb interlayer demonstrate enhanced 22.31% power conversion efficiency from efficient electron extraction capability and exhibit excellent photo- and thermal stability due to suppressed ion migration.

To investigate the synergistic effect of perylene diimide (PDI) unit and diphenyl-o-carboranyl (Cb) group, PDI–Cb with Cb groups at the bay positions of the PDI unit is synthesized. By introducing 3D carboranyl group into the bay position, PDI–Cb shows distorted geometry between PDI core and the adjacent phenyl ring of Cb due to the ring torsions, which can suppress the aggregation tendency. Furthermore, the proper lowest unoccupied molecular orbital (LUMO) energy level of −4.12 eV may be beneficial to extract electrons from the perovskite efficiently. By introducing PDI–Cb interlayer at perovskite/C60 interface, the inverted perovskite solar cells (PSCs) have significantly enhanced efficiency from 19.98% to 22.31% at 1 sun condition (AM1.5G 100 mW cm⁻²) because the PDI–Cb interlayer promotes charge extraction thanks to the electron-accepting ability of Cb group; thereby, it reduces carrier recombination significantly. In addition, the unencapsulated inverted PSC with the PDI–Cb interlayer has good photo- and thermal stability because it shows 9.3% efficiency degradation after continuous 1 sun light soaking for 1000 h at 85 °C in N₂ atmosphere.

A universal perovskite surface passivation method using 2,5-thiophenedicarboxylic acid is developed, by which the V _OC of different CsPbX₃ solar cells are highly enhanced, leaving extremely small V _OC deficits.

Abstract

In comparison to hybrid perovskite solar cells (PSCs), all-inorganic CsPbX₃ PSCs suffer from larger V _OC deficits, leading to inferior efficiency. The perovskite surface defects like iodine vacancy (V_I) are the main sources of nonradiative recombination causing a V _OC deficit. Here, 2,5-thiophenedicarboxylic acid (TDCA) is used to passivate the surface V_I through the strong coordination interaction between the thiophene unit of TDCA and the undercoordinated Pb²⁺ of perovskite. TDCA passivation also elevates the perovskite surface valence band position, leading to a better interfacial energy alignment. Consequently, the V _OC of CsPbI_2.25Br_0.75 PSCs is remarkably improved from 1.36 to 1.43 V (efficiency from 15.55% to 16.72%), reaching 92% (record-high among CsPbX₃ PSCs) of the Shockley–Queisser V _OC limit. This method also promotes the V _OC of CsPbI_1.5Br_1.5 cell from 1.42 to 1.51 V (90% of the limit) and CsPbIBr₂ cell from 1.44 to 1.54 V (87% of the limit), demonstrating its universality for CsPbX₃ perovskites.

The overview and outlook on graphene- and carbon nanotube-applied perovskite solar cells for both single-junction and tandem applications in this review provide an insight to research strategies for nanocarbons and optoelectronics. The versatile roles and synthesis methods of applied nanocarbons in perovskite solar cells open a gateway to next-generation energy harvesting devices in terms of both performance and functionality.

Abstract

Nanocarbon materials, such as graphene and carbon nanotubes (CNTs), have attracted considerable attention as the main or supplementary components in various optoelectronics boosting the device performance and improving the process conditions. Specifically, their application to perovskite solar cells, which are among the most promising photovoltaic devices acknowledged for eco-friendly energy generation, has significantly impacted the current standing of metal halide perovskite-based devices. The uniqueness of the nanocarbon applications can be attributed to their outstanding optical, electrical, chemical and mechanical properties, which conventional materials do not possess. This review overviews past and present reports on graphene- and CNT-incorporated perovskite solar cells. Versatile roles and various synthetic methodologies of the applied nanocarbons in perovskite solar cells, including the material growth methods and sources, and functions as transparent electrodes, charge-transporting layers, interfacial layers, additives and encapsulants, are categorized and graphically illustrated. The discussion expands from single-junction to tandem applications with silicon solar cells, where the nanocarbon materials also play an equally important yet divergent function. Applications of each graphene and CNTs to the silicon-perovskite tandem solar cells are interpreted in terms of what roles they play and how they solve the conventional problems. This review serves as the guideline for the photovoltaics researchers in advancing devices using nanocarbons.

Network topology derived from grain subdivision and grain slip enables simultaneous robust toughness and strength of perovskite films with the elongation at break of 5.02% and the fracture strength of 55.25 MPa, respectively. The flexible solar cells achieve a champion power conversion efficiency of 20.01% and remaining 90% of the initial efficiency after bending 6000 cycles at the 2 mm curvature radius.

Abstract

The toughness and strength are generally mutually exclusive for most materials. Although the biological materials in nature such as wood, bone, and nacre exhibit outstanding toughness by forming hierarchical multiscale (nano to macro) structures, it is a huge challenge to simultaneously obtain excellent strength and toughness from material synthesis. Here, one kind of network topology is observed by introducing sodium hyaluronate into organometallic halide perovskite film to greatly improve its strength and toughness. The grain slip and grain subdivision under tensile stress are schemed to dissipate the system energy and endow the perovskite film with remarkable toughness. Meanwhile, the subdivided grains linked by sodium hyaluronate through strong interaction result in high strength of perovskite film. As a result, the perovskite films exhibit robust enhancements with the elongation at break from 1.58% to 5.02% and the fracture strength from 23.13 to 55.25 MPa. It is worth noting that the efficiency of inverted flexible perovskite solar cells reaches 20.01% as well as maintains 90% of the initial efficiency after 6000 cycles of bending at a 2 mm curvature radius. This work devises a topology structure to overcome the conflict between toughness and strength of perovskite films for wearable electronics.

New synthesized non-conjugated polyelectrolyte is introduced as an interfacial layer between the charge-transport layer and perovskite absorbent, which significantly reduce both bulk and interfacial nonradiative recombination losses, but also aligns the interface's energy level. The modified perovskite solar cells show a power conversion efficiency of 24.4% (open-circuit voltage 1.21 V) with negligible hysteresis and superior operational stability.

Abstract

Suppressing nonradiative recombination at the interface between the organometal halide perovskite (PVK) and the charge-transport layer (CTL) is crucial for improving the efficiency and stability of PVK-based solar cells (PSCs). Here, a new bathocuproine (BCP)-based nonconjugated polyelectrolyte (poly-BCP) is synthesized and this is introduced as a “dual-side passivation layer” between the tin oxide (SnO₂) CTL and the PVK absorber. Poly-BCP significantly suppresses both bulk and interfacial nonradiative recombination by passivating oxygen-vacancy defects from the SnO₂ side and simultaneously scavenges ionic defects from the other (PVK) side. Therefore, PSCs with poly-BCP exhibits a high power conversion efficiency (PCE) of 24.4% and a high open-circuit voltage of 1.21 V with a reduced voltage loss (PVK bandgap of 1.56 eV). The non-encapsulated PSCs also show excellent long-term stability by retaining 93% of the initial PCE after 700 h under continuous 1-sun irradiation in nitrogen atmosphere conditions.

Publication date: November 2022

Source: Nano Energy, Volume 102

Author(s): Qixin Zhuang, Cong Zhang, Cheng Gong, Haiyun Li, Hongxiang Li, Zhongying Zhang, Hua Yang, Jiangzhao Chen, Zhigang Zang

Nature Energy, Published online: 29 August 2022; doi:10.1038/s41560-022-01102-w

Terminal groups matter: A spiro-typed hole-transporting material (spiro-carbazole) with N-ethylcarbazole units as terminal groups is designed. It exhibits lower highest occupied molecular orbital level, higher glass transition temperature and hole mobility, as well as better hydrophobicity than conventional spiro-OMeTAD, leading to better device efficiency and stability in perovskite solar cells.

Abstract

The development of stable and efficient hole-transporting materials (HTMs) is critical for the commercialization of perovskite solar cells (PSCs). Herein, a novel spiro-type HTM was designed and synthesized where N-ethylcarbazole-terminated groups fully substituted the methoxy group of spiro-OMeTAD, named spiro-carbazole. The developed molecule exhibited a lower highest occupied molecular orbital level, higher hole mobility, and extremely high glass transition temperature (T _g=196 °C) compared with spiro-OMeTAD. PSCs with the developed molecule exhibited a champion power conversion efficiency (PCE) of 22.01 %, which surpassed traditional spiro-OMeTAD (21.12 %). Importantly, the spiro-carbazole-based device had dramatically better thermal, humid, and long-term stability than spiro-OMeTAD.