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Transcatheter arterial chemoembolization (TACE) has been widely used in clinical practice as a first-line treatment for unresectable hepatocellular carcinoma (HCC). However, the current therapeutic effect of TACE is far from satisfactory and thus requires further improvement. TACE combined with multifunctional magnetic particles may be a promising approach for the treatment of HCC. In this study, we designed a new magnetic drug carrier system consisting of micron-sized iron powder, barium ferrite (BaFe12O19), and carbon-coated iron nanocrystals (CCINs). CCINs possess properties, such as high drug loading and sustained release. BaFe12O19 could attract both CCINs and iron powder to form larger clusters after magnetization. Altogether, the triple therapeutic effects of chemotherapeutic enhancement, embolization, and thermal ablation could be realized herein. Further experiments indicate that the system has a high drug-loading capacity, good controlled-release effect, and no significant cytotoxicity. Under the action of a medium-frequency magnetic induction device, the magnetic induction temperature could reach 43 °C in one min while the maximum temperature of 70.8 °C could be reached in 2.5 hours. Overall, this new carrier system displayed excellent antitumor effects in a mouse model. Our findings demonstrate the great application prospects of this system in TACE for HCC.

Defect-induced charge carrier recombination at the interfaces between perovskite and adjacent charge transport layers restricts further improvements in the device performance of perovskite solar cells (PSCs). Defect passivation at these interfaces can reduce trap states and inhibit the induced nonradiative recombination. Herein, we report a double-sided interfacial passivation via simply evaporating potassium chloride (DIP-KCl) at both the hole transport layer (HTL)/perovskite and perovskite/electron transport layer (ETL) interfaces in inverted planar PSCs. We demonstrate that the bottom KCl layer at the HTL/perovskite interface not only reduces the interfacial defects and improves the interfacial contact, but also leads to increased perovskite crystallinity, while the top KCl layer at the perovskite/ETL interface efficiently passivates the perovskite top surface defects and facilitates electron extraction at this interface. Thus, suppressed nonradiative recombination and faster charge extraction at both interfaces close to the perovskite layer can be achieved by using our DIP-KCl strategy. As a result, inverted PSCs based on DIP-KCl present an increased efficiency from 17.1% to 19.2% and enhanced stability, retaining over 90% of their initial efficiency after aging at maximum power point tracking for 1000 h. This work provides a simple and efficient way for defect passivation to further increase the efficiency and stability of PSCs.

The electron transport layer (ETL) plays a critical role in charge extraction and perovskite thin film growth in planar n–i–p heterojunction perovskite solar cells. Herein, we modulated the nucleation and growth rate of CsPbI3 crystals by using a Mo doping strategy to synthesize high-quality SnO2 crystals as an ETL nano-film in n–i–p heterojunction perovskite solar cells. We revealed that such a nano-film with low surface energy and high roughness induced by Mo doping provides seed-like nucleation sites for CsPbI3 inorganic perovskite growth, leading to improved perovskite film morphology. The charge extraction at the ETL/perovskite interface is also enhanced due to the improved energy level alignment. As a result, a high power conversion efficiency of 17.41% can be achieved under one sun irradiation for a planar n–i–p heterojunction structured CsPbI3 solar cell by using this novel Mo–SnO2 ETL. This work provides a simple pathway to simultaneously modulate CsPbI3 inorganic perovskite crystallization and interfacial charge extraction in planar heterojunction perovskite devices.

The upscaling of perovskite solar cells to module scale and long-term stability have been recognized as the most important challenges for the commercialization of this emerging photovoltaic technology. In a perovskite solar module, each interface within the device contributes to the efficiency and stability of the module. Here, we employed a holistic interface stabilization strategy by modifying all the relevant layers and interfaces, namely the perovskite layer, charge transporting layers and device encapsulation, to improve the efficiency and stability of perovskite solar modules. The treatments were selected for their compatibility with low-temperature scalable processing and the module scribing steps. Our unencapsulated perovskite solar modules achieved a reverse-scan efficiency of 16.6% for a designated area of 22.4 cm2. The encapsulated perovskite solar modules, which show efficiencies similar to the unencapsulated one, retained approximately 86% of the initial performance after continuous operation for 2,000 h under AM1.5G light illumination, which translates into a T90 lifetime (the time over which the device efficiency reduces to 90% of its initial value) of 1,570 h and an estimated T80 lifetime (the time over which the device efficiency reduces to 80% of its initial value) of 2,680 h. The upscaling of layer treatments and processing that afford high efficiency and stability in small-area perovskite solar cells remains challenging. Liu et al. show how the efficiency and stability of perovskite modules can be improved using an integrated approach to interface and layer engineering.

The booming growth of organic-inorganic hybrid lead halide perovskite solar cells have made this promising photovoltaic technology to leap towards commercialization. One of the most important issues for the evolution from research to practical application of this technology is to achieve high-throughput manufacturing of large-scale perovskite solar modules. In particular, realization of scalable fabrication of large-area perovskite films is one of the essential steps. During the past ten years, a great number of approaches have been developed to deposit high quality perovskite films, to which additives are introduced during the fabrication process of perovskite layers in terms of the perovskite grain growth control, defect reduction, stability enhancement, etc. Herein, we first review the recent progress on additives during the fabrication of large area perovskite films for large scale perovskite solar cells and modules. We then focus on a comprehensive and in-depth understanding of the roles of additives for perovskite grain growth control, defects reduction, and stability enhancement. Further advancement of the scalable fabrication of high-quality perovskite films and solar cells using additives to further develop large area, stable perovskite solar cells are discussed.

Control of forward and inverse reactions between perovskites and precursor materials is key to attaining high-quality perovskite materials. Many techniques focus on synthesizing nanostructured CsPbX3 materials (e.g., nanowires) via a forward reaction (CsX + PbX2 → CsPbX3). However, low solubility of inorganic perovskites and complex phase transition make it difficult to realize the precise control of composition and length of nanowires using the conventional forward approach. Herein, we report the self-assembly inverse growth of CsPbBr3 micronanowires (MWs) (CsPb2Br5 → CsPbBr3 + PbBr2↑) by controlling phase transition from CsPb2Br5 to CsPbBr3. The two-dimensional (2D) structure of CsPb2Br5 serves as nucleation sites to induce initial CsPbBr3 MW growth. Also, phase transition allows crystal rearrangement and slows down crystal growth, which facilitates the MW growth of CsPbBr3 crystals along the 2D planes of CsPb2Br5. A CsPbBr3 MW photodetector constructed based on the inverse growth shows a high responsivity of 6.44 A W–1 and detectivity of ∼1012 Jones. Large grain size, high crystallinity, and large thickness can effectively alleviate decomposition/degradation of perovskites, which leads to storage stability for over 60 days in humid environment (relative humidity = 45%) and operational stability for over 3000 min under illumination (wavelength = 400 nm, light intensity = 20.06 mW cm–2).

All-inorganic halide perovskites are promising materials for optoelectronic applications. The surface or interface structure of the perovskites plays a crucial role in determining the optoelectronic conversion efficiency, as well as the material stability. A thorough understanding of surface atomic structures of the inorganic perovskites and their contributions to their optoelectronic properties and stability is lacking. Here we show a scanning tunneling microscopy investigation on the atomic and electronic structure of CsPbBr3 perovskite. Two different surface structures with a stripe and an armchair domain are identified, which originates from a complex interplay between Cs cations and Br anions. Our findings are further supported and correlated with density functional theory calculations and photoemission spectroscopy measurements. The stability evaluation of photovoltaic devices indicates a higher stability for CsPbBr3 in comparison with MAPbBr3, which is closely related to the low volatility of Cs from the perovskite surface.

Lead-free double perovskite materials have attracted much interest for optoelectronic applications due to their nontoxicity and high stability. In this work, centimetre-sized Cs2AgBiBr6 single crystals were successfully grown using methylammonium bromide (MABr) as the flux by a top-seeded solution growth (TSSG) method. The low-temperature crystal structure of Cs2AgBiBr6 single crystals was determined and refined. To investigate the interface problems between Cs2AgBiBr6 single crystals and electrodes, the optical band gap, X-ray photoelectron spectroscopy (XPS), and ultraviolet photoemission spectroscopy (UPS) measurements were performed on Cs2AgBiBr6 single crystals. More importantly, we investigated the photodetectors based on Cs2AgBiBr6 single crystals with different contact electrodes (Au, Ag, and Al). It is found that a good Ohmic contact with Ag electrodes enables excellent photo-response behaviors. Furthermore, we studied the photodetectors based on Cs2AgBiBr6 single crystals using Ag electrodes under room and low temperature conditions, which underwent phase transition. Cs2AgBiBr6 single crystal photodetectors show clear differences at room and low temperatures, which is caused by the work function changes of Cs2AgBiBr6 single crystals induced by the reversible phase transition. These attractive properties may enable opportunities to apply emerging double perovskite single-crystalline materials for high-performance optoelectronic devices.

Hybrid chemical vapor deposition (HCVD) has been employed in the fabrication of perovskite solar cells (PSCs) and modules (PSMs), and it shows strong promise for upscalable fabrication. The conventional HCVD process needs a relatively long processing time (e.g., several hours) and the fabricated PSCs often exhibit salient hysteresis, which impedes utilization of this technology for mass production. Herein, we demonstrate a rapid HCVD (RHCVD) fabrication process for PSCs using a rapid thermal process, which not only significantly reduces the deposition time to less than 10 min, but also effectively suppresses hysteresis. This markedly reduced deposition time is comparable to that of solution-coating processes. Furthermore, the shorter processing time inside the furnace reduces the exposure time of the glass/ITO/SnO2 substrates under vacuum, which helps maintain the high quality of the SnO2 electron-transport layer and results in a lower density of gap states. Finally, PSMs with a designated area of 22.4 cm2 fabricated via RHCVD achieved an efficiency of 12.3%, and maintained 90% of the initial value after operation under continuous light illumination for over 800 h.

A series of challenging issues such as field-driven spectral drift for the CsPbClxBr3–x system and mixed phases in quasi-two-dimensional structures still exist when devising blue-emitting perovskites. In this Letter, the CsPbBr3 quantum-dot (QD) system is proposed to overcome these challenges. However, to date, the CsPbBr3 QD films with tunable colors from green to blue still cannot be achieved using existing methods. Herein, a simple one-step spin-coating route incorporated with efficient ligand passivation is developed to realize this goal. The size restriction of CsPbBr3 QDs is enabled by a diammonium ligand, propane-1,3-diammonium bromide (PDAB). A mixed-ligand system of phenethylammonium bromide (PEAB) with PDAB is further explored to enhance their optical performance. The CsPbBr3 QDs experience a second growth process upon controlled air exposure, which is utilized to realize their size control and emission wavelength tunability. The CsPbBr3 QD-based devices exhibit no spectral drift in electroluminescence under voltage bias.

Carbon electrode-based perovskite solar cells (PSCs) with low-cost and long-term stability have been recognized as a competitive candidate toward future practical applications. However, energy leve...

In recent years, the major factors that determine commercialization of perovskite photovoltaic technology have been shifting from solar cell performance to stability, reproducibility, device upscaling and the prevention of lead (Pb) leakage from the module over the device service life. Here we simulate a realistic scenario in which perovskite modules with different encapsulation methods are mechanically damaged by a hail impact (modified FM 44787 standard) and quantitatively measure the Pb leakage rates under a variety of weather conditions. We demonstrate that the encapsulation method based on an epoxy resin reduces the Pb leakage rate by a factor of 375 compared with the encapsulation method based on a glass cover with an ultraviolet-cured resin at the module edges. The greater Pb leakage reduction of the epoxy resin encapsulation is associated with its optimal self-healing characteristics under the operating conditions and with its increased mechanical strength. These findings strongly suggest that perovskite photovoltaic products can be deployed with minimal Pb leakage if appropriate encapsulation is employed. Lead leakage from damaged perovskite solar cells poses a challenge to the deployment of such technology. Here, Jiang, Qiu and co-workers quantify lead leakage caused by a simulated hail impact under a number of weather conditions and show that self-healing encapsulations can effectively reduce it.

The development of scalable deposition methods for stable perovskite layers is a prerequisite for the development and future commercialization of perovskite solar modules. However, there are two major challenges, i.e., scalability and stability. In sharp contrast to a previous report, here we develop a fully vapor based scalable hybrid chemical vapor deposition (HCVD) process for depositing Cs-formamidinium (FA) mixed cation perovskite films, which alleviates the problem encountered when using conventional solution coating of mainly methylammonium lead iodide (MAPbI3). Using our HCVD method, we fabricate perovskite films of Cs0.1FA0.9PbI2.9Br0.1 with enhanced thermal and phase stabilities, by the intimate incorporation of Cs into FA based perovskite films. In addition, the SnO2 electron transport layer (ETL) (prepared by sputter deposition) is found to be damaged during the HCVD process. In combination with precise interface engineering of the SnO2 ETL, we demonstrate relatively large area solar modules with efficiency approaching 10% and with a designated area of 91.8 cm2 fabricated on 10 cm × 10 cm substrates (14 cells in series). On the basis of our preliminary operational stability tests on encapsulated perovskite solar modules, we extrapolated that the T80 lifetime is approximately 500 h (under the light illumination of 1 sun and 25 °C).

Perovskite solar cells have emerged as the next‐generation high‐efficiency solar cell, but their absorption is mostly limited to the visible (vis) range. One possible solution is to integrate near‐infrared (NIR)‐to‐vis photon upconversion (UC). Herein, we show the first example of endowing perovskite solar cells with NIR sensitivity by using solid films showing NIR‐to‐vis UC based on triplet‐triplet annihilation (TTA). A high TTA‐UC efficiency of 4.1±0.3 % at an excitation intensity of 125 W/cm² is achieved by sensitizing a rubrene (acceptor) triplet with an osmium (Os) complex donor having singlet‐to‐triplet (S−T) absorption in the NIR range, and by increasing the fluorescence quantum yield through energy harvesting to a highly fluorescent collector. In particular, our spectroscopic studies indicate that the upconverted acceptor singlet energy is almost selectively transferred to the collector rather than being quenched by the donor. By attaching the TTA‐UC film behind a semi‐transparent perovskite solar cell, a photocurrent generation is observed under excitation at 938 nm.

Besides high efficiency, the stability and reproducibility of perovskite solar cells (PSCs) are also key for their commercialization. Herein, we report a simple perovskite formation method to fabricate perovskite films with thickness over 1 μm in ambient condition on the basis of the fast gas−solid reaction of chlorine-incorporated hydrogen lead triiodide and methylamine gas. The resultant thick and smooth chlorine-incorporated perovskite films exhibit full coverage, improved crystallinity, low surface roughness and low thickness variation. The resultant PSCs achieve an average power conversion efficiency of 19.1 ± 0.4% with good reproducibility. Meanwhile, this method enables an active area efficiency of 15.3% for 5 cm × 5 cm solar modules. The un-encapsulated PSCs exhibit an excellent T80 lifetime exceeding 1600 h under continuous operation conditions in dry nitrogen environment.

The rapid development of perovskite solar cells (PSCs) in view of efficiency during the past decade has made this emerging photovoltaic (PV) technology a promising competitor in the PV market. In the next step, PSCs need be manufactured into module scale to meet the commercialization requirements for further practical application. Demonstrations of perovskite solar modules (PSMs) and their improvements in efficiency and stability have recently become an intense area of research activities. Minimodules with the size suitable for laboratory investigation are naturally recognized as a desirable model for the study of PSMs. Herein, the recent progress and challenges in perovskite solar minimodules and the efforts to improve their scalable fabrication, efficiency, and stability are reviewed. Minimodule architectures, minimodule fabrication, and progress in the scalable deposition of perovskite and charge-transport layers as well as minimodule encapsulation are also discussed.

Organic-inorganic perovskite solar cells have been highlighted as one of the most competitive thin film photovoltaics recently. It is promising to further raise the power conversion efficiency if high quality absorber is coupled with rational optical design for effective photon management. Here we demonstrate the implementation of perovskite nanostructure assembly by simple solution process to interfere the propagation of light inside the adjacent absorber. It enhances light harvesting to obtain higher attainable photocurrents and photovoltage in the resultant devices, achieving a decent power conversion efficiency (PCE) over 19% consequently. The presented nanostructure assembly integrates perovskite materials with desirable processibility and chemical compatibility by chemical synthesis and interface modification. For the first time, a synergetic localized “gratings” and enhanced fluorescence effect was demonstrated to govern photon management in perovskite solar cells. These findings may serve as a general guide to design and construct perovskite thin solar cells with efficiency approaching Shockley-Queisser limit.

Organic–inorganic hybrid perovskites with mixed organic cations and/or halides have attracted increasing attention due to their superior optoelectronic properties, which are tailorable for different applications. To obtain a deeper understanding of materials properties, single crystals are regarded as the best platform among various building blocks for fundamental study. Here, we synthesized a series of perovskite single crystals with mixed organic cations (APbI3, A = CH3NH3+, MA+; or CH(NH2)2+, FA+) along the compositional space, and conducted a systematic investigation to correlate the carrier behavior with the organic cations. The single crystals were synthesized via inverse temperature crystallization assisted by hydroiodic acid, where the quality of the crystals could be judiciously controlled by the thermodynamic process. It is found that the substitution of 15% MA+ in FAPbI3 single crystals stabilizes the phase with the best charge transport characteristics. Both photodetector and J–V measurements suggested that FA0.85MA0.15PbI3 single crystal exhibits suppressed ion migration compared with the counterpart FA0.15MA0.85PbI3 single crystal. These results represent an important step to highlight the role of organic cations in hybrid perovskite materials, which will further benefit fundamental understanding of materials and device optimization.

Here, a low-temperature solution-processed nickel oxide (NiOx) thin film was first employed as a hole transport layer in both inverted (p-i-n) planar and regular (n-i-p) mesoscopic organic–inorganic hybrid perovskite solar cells (PVSCs). In p-i-n PVSCs, the wetting properties, perovskite morphology, absorption and hole extraction process can be significantly enhanced with a suitable surface treatment, resulting in a significantly increased fill factor (from 0.684 to 0.742) and short circuit current density (from 16.73 to 20.66 mA cm−2). On the basis of the treated NiOx thin film, a promising power conversion efficiency of 15.9% with negligible hysteresis was obtained for inverted planar PVSCs, and 11.8% was obtained for the flexible devices. More importantly, the presynthesized NiOx can be directly deposited on the perovskite film as a top hole transport layer without decomposing the perovskite in n-i-p PVSCs. The resulting n-i-p device shows a five-fold improvement in power conversion efficiency when compared with a hole transport material free device, which indicates that this solution-processed NiOx is promising for all-inorganic charge selection layer based, stable and low cost PVSCs.

Hybrid organic–inorganic perovskite materials offer a range of interesting characteristics that are suitable for optoelectronic devices, such as photovoltaics. Along with the fast rise in device performance, a current density–voltage (J–V) hysteresis originating from defects and their movement has attracted intense attention, which renders challenges regarding the stability and reliability of the novel materials. Here, we carefully probe the effects of defects in perovskite materials and across interfaces within the device, in which bistable conductive states are achieved for the next generation of nonvolatile memory. The memory device shows an operating voltage as low as 0.25 V, and a decent ON/OFF ratio. More importantly, we correlate the defect density and hysteresis-index of different perovskite films with the corresponding memory device performance. The findings enrich our understanding of the working mechanism of perovskite memory devices, which will also benefit other organic–inorganic hybrid perovskite optoelectronics.

Crystal orientation has a great impact on the properties of perovskite films and the resultant device performance. Up to now, the exquisite control of crystal orientation (the preferred crystallographic planes and the crystal stacking mode with respect to the particular planes) in mixed-cation perovskites has received limited success, and the underlying mechanism that governs device performance is still not clear. Here, a thermodynamically favored crystal orientation in formamidinium/methylammonium (FA/MA) mixed-cation perovskites is finely tuned by composition engineering. Density functional theory calculations reveal that the FA/MA ratio affects the surface energy of the mixed perovskites, leading to the variation of preferential orientation consequently. The preferable growth along the (001) crystal plane, when lying parallel to the substrates, affects their charge transportation and collection properties. Under the optimized condition, the mixed-cation perovskite (FA1- x MAx PbI2.87 Br0.13 (Cl)) solar cells deliver a champion power conversion efficiency over 21%, with a certified efficiency of 20.50 ± 0.50%. The present work not only provides a vital step in understanding the intrinsic properties of mixed-cation perovskites but also lays the foundation for further investigation and application in perovskite optoelectronics.

Perovskite solar cells (PSCs) are arising as strong candidates for the next generation of thin-film photovoltaic techniques due to their high efficiency, low-cost, and simple manufacture process. A PSC usually is consisted of several components including in conductive bottom substrate, electron or hole transport layer, perovskite layer, and a counter electrode. However, PSCs are facing issues such as inaccurate evaluation of power conversion efficiency due to hysteresis, poor long-term stability, an inability for continuous manufacturing large area cells, and the use of noble metal as counter electrodes. In fact, a counter electrode is one of the key factors that govern the charge collection, long-term stability, and total cost of PSCs. Despite its importance, less attention has been paid to the exploration of counter electrode materials for PSCs. Here, we provided a summary of the recent development of counter electrode for PSCs, including metal thin-film electrode, super-thin metal thin-film electrode, nanostructured metal electrode, graphene electrode, carbon nanotube electrode, carbon black/graphite electrode, conductive oxide electrode, and polymer electrode. We highlighted findings of novel counter electrode materials towards low cost and stable PSCs as well as some drawbacks with an aim to provide readers a concise overview of the field for developing new counter electrode materials.

Efficient and stable parallel perovskite solar module is achieved by slot-die coating., Perovskite solar cells have emerged as one of the most promising thin-film photovoltaic (PV) technologies and have made a strong debut in the PV field. However, they still face difficulties with up-scaling to module-level devices and long-term stability issue. Here, we report the use of a room-temperature nonvolatile Lewis base additive, diphenyl sulfoxide(DPSO), in formamidinium-cesium (FACs) perovskite precursor solution to enhance the nucleation barrier and stabilize the wet precursor film for the scalable fabrication of uniform, large-area FACs perovskite films. With a parallel-interconnected module design, the resultant solar module realized a certified quasi-stabilized efficiency of 16.63% with an active area of 20.77 cm2. The encapsulated modules maintained 97 and 95% of their initial efficiencies after 10,000 and 1187 hours under day/night cycling and 1-sun equivalent white-light light-emitting diode array illumination with maximum power point tracking at 50°C, respectively.

As the increasing demand for thermal performance of mechanical products, thermal contact conductance (TCC) is widely used in the thermal-mechanical analysis. This paper presents a TCC prediction model based on fractal geometry. Besides the fractal dimension and fractal roughness parameter, the fractal domain area is estimated according to the fractal characteristics of the surface topography. Based on these three fractal parameters, the TCC of the interface with or without fluidic interface material can be calculated. The experimental results show that the fractal model is superior to the TCC models based on GW geometry in accuracy and numerical stability.

Solar cells based on metal halide perovskites have emerged as a promising low-cost photovoltaic technology. In contrast to inert atmospheres where most of the lab-scale devices are made to date, large-area low-cost production of perovskite solar cells often involves processing of perovskites in various atmospheres including ambient air, nitrogen, and/or vacuum. Herein, the impact of atmosphere on the energy levels of methylammonium lead halide perovskite films is systematically investigated. The atmosphere is varied to simulate the typical fabrication process. Through a comprehensive analysis combining the Fermi level evolution, surface photovoltage, photoluminescence properties, photovoltaic performance, and device simulation, an overall landscape of the energy diagram of the perovskite layer is able to be determined. The findings have direct implications for real-world devices under typical atmospheres, and provide insights into the fabrication-process design and optimization. Furthermore, a universal Fermi level shift under vacuum for lead halide-based perovskites revealed in this study, urges a refreshed view on the energetics studies conducted without considering the atmospheric effect.

Perovskite solar cells (PSCs) have attracted great attention in the past few years due to their rapid increase in efficiency and low-cost fabrication. However, instability against thermal stress and humidity is a big issue hindering their commercialization and practical applications. Here, by combining thermally stable formamidinium-cesium-based perovskite and a moisture-resistant carbon electrode, successful fabrication of stable PSCs is reported, which maintain on average 77% of the initial value after being aged for 192 h under conditions of 85 degrees C and 85% relative humidity (the "double 85" aging condition) without encapsulation. However, the mismatch of energy levels at the interface between the perovskite and the carbon electrode limits charge collection and leads to poor device performance. To address this issue, a thin-layer of poly(ethylene oxide) (PEO) is introduced to achieve improved interfacial energy level alignment, which is verified by ultraviolet photoemission spectroscopy measurements. Indeed as a result, power conversion efficiency increases from 12.2% to 14.9% after suitable energy level modification by intentionally introducing a thin layer of PEO at the perovskite/carbon interface.

Replacement of the ZrO2 insulator layer in the state-of-the-art TiO2/ZrO2/carbon structure by mesoscopic p-type NiO particles led to 39% increase of energy conversion efficiency of hole-conductor-free organometallic perovskite heterojunction solar cells with carbon counter electrodes. In these cells, the light absorber, CH3NH3PbI3, formed instantly inside the pores of the entire TiO2/NiO/carbon layer upon sequential deposition of PbI2 and CH3NH3I. Photoluminescence, impedance spectroscopy and transient photovoltage decay measurements have revealed that introduction of NiO extended the electron lifetime and augmented the hole extraction of the counter electrode. As a result, the photocurrent and open-circuit voltage both increased, resulting in a cell with impressive energy conversion efficiency of 11.4% under AM1.5G conditions.

Herein, we present fully printable carbon electrode based perovskite solar cells using highly crystalline NiO nanosheets as top hole transport layers, mesoporous TiO2 nanoparticles as a bottom electron transport layer and ZrO2 as an intermediate spacer layer, respectively. Time-resolved photoluminescence decay measurements, electron impedance spectroscopy and transient photovoltage decay measurements have revealed that the NiO nanosheets as top hole transporters exhibit superior charge collection efficiency and a prolonged charge lifetime. As a result, an impressive power conversion efficiency of 14.2% is achieved under standard testing conditions.

In this study, new pull-push arylamine-fluorene based organic dyes zzx-op1, zzx-op2, and zzx-op3 have been designed and synthesized for p-type dye-sensitized solar cells (p-DSCs). In zzx-op1, a di(p-carboxyphenyl)amine (DCPA) was used as an electron donor, a perylenemonoimide (PMID) as an electron acceptor, and a fluorene (FLU) unit with two aliphatic hexyl chains as a π-conjugated linker. In zzx-op2 and zzx-op3, a 3,4-ethylenedioxythiophene (EDOT) and a thiophene were inserted consecutively between PMID and FLU to tune the energy levels of the frontier molecular orbitals of the dyes. The structural modification broadened the spectral coverage from an onset of 700 nm for zzx-op1 to 750 nm for zzx-op3. The electron-rich EDOT and thiophene lifted up the HOMO (highest occupied molecular orbital) levels of zzx-op2 and zzx-op3, making their potential more negative than zzx-op1. When three dyes were employed in p-type DSCs with I(-)/I3(-) as a redox couple and NiO nanoparticles as hole materials, zzx-op1 exhibited impressive energy conversion efficiency of 0.184% with the open-circuit voltage (VOC) of 112 mV and the short-circuit current density (JSC) of 4.36 mA cm(-2) under AM 1.5G condition. Density functional theory calculations, transient photovoltage decay measurements, and electrochemical impedance spectroscopic studies revealed that zzx-op1 sensitized solar cell exhibited much higher charge injection efficiency (90.3%) than zzx-op2 (53.9%) and zzx-op3 (39.0%), indicating a trade-off between spectral broadening and electron injection driving force in p-type DSCs.

High efficiency and long-term stability are vital for further development of perovskite solar cells (PSCs). PSCs based on cesium lead halide perovskites exhibit better stability but lower power conversion efficiencies (PCEs), compared with organic-inorganic hybrid perovskites. Lower PCE is likely associated with trap defects, overgrowth of partial crystals and irreversible phase transition in the films. Here we introduce a strategy to fabricate high-efficiency CsPbBr3-based PSCs by controlling the ratio of CsBr and PbBr2 to form the perovskite derivative phases (CsPb2Br5/Cs4PbBr6) via a vapor growth method. Following post-annealing, the perovskite derivative phases as nucleation sites transform to the pure CsPbBr3 phase accompanied by crystal rearrangements and retard rapid recrystallization of perovskite grains. This growth procedure induced by phase transition not only makes the grain size of perovskite films more uniform, but also lowers the surface potential barrier that existsbetween the crystals and grain boundaries. Owing to the improved film quality, a PCE of 10.91% was achieved for n-i-p structured PSCs with silver electrodes, and a PCE of 9.86% for hole-transport-layer-free devices with carbon electrodes. Moreover, the carbon electrode-based devices exhibited excellent long-term stability and retained 80% of the initial efficiency in ambient air for more than 2000 h without any encapsulation.

An upscalable perovskite film deposition method combining raster ultrasonic spray coating and chemical vapor deposition is reported. This method overcomes the coating size limitation of the existing stationary spray, single‐pass spray, and spin‐coating methods. In contrast with the spin‐coating method (>90% Pb waste), negligible Pb waste during PbI2 deposition makes this method more environmentally friendly. Outstanding film uniformity across the entire area of 5 cm × 5 cm is confirmed by both large‐area compatible characterization methods (electroluminescence and scattered light imaging) and local characterization methods (atomic force microscopy, scanning electron microscopy, photoluminescence mapping, UV–vis, and X‐ray diffraction measurements on multiple sample locations), resulting in low solar cell performance decrease upon increasing device area. With the FAPb(I0.85Br0.15)3 (FA = formamidinium) perovskite layer deposited by this method, champion solar modules show a power conversion efficiency of 14.7% on an active area of 12.0 cm2 and an outstanding shelf stability (only 3.6% relative power conversion efficiency decay after 3600 h aging). Under continuous operation (1 sun light illumination, maximum power point condition, dry N2 atmosphere with

The coordination effects of additives during perovskite crystal growth are investigated, and a novel technique to fabricate high-quality perovskite thin films by introduction of weak coordination additives (e.g., acetonitrile) in the precursors is demonstrated.

Here, we demonstrate an effective low-temperature approach to fabricate a uniform and pinhole-free compact TiO2 layer for enhancing photovoltaic performance of perovskite solar cells. TiCl4 was used to modify TiO2 for efficient charge generation and significantly reduced recombination loss. We found that a TiO2 layer with an appropriate TiCl4 treatment possesses a smooth surface with full coverage of the conductive electrode. Further studies on charge carrier dynamics confirmed that the TiCl4 treatment improves the contact of the TiO2/perovskite interface, facilitating charge extraction and suppressing charge recombination. On the basis of the treatment, we improved the open circuit voltage from 1.01 V of the reference cell to 1.08 V, and achieved a power conversion efficiency of 16.4%.

Hybrid perovskites have shown astonishing power conversion efficiencies owed to their remarkable absorber characteristics including long carrier lifetimes, and a relatively substantial defect tolerance for solution-processed polycrystalline films. However, nonradiative charge carrier recombination at grain boundaries limits open circuit voltages and consequent performance improvements of perovskite solar cells. Here we address such recombination pathways and demonstrate a passivation effect through guanidinium-based additives to achieve extraordinarily enhanced carrier lifetimes and higher obtainable open circuit voltages. Time-resolved photoluminescence measurements yield carrier lifetimes in guanidinium-based films an order of magnitude greater than pure-methylammonium counterparts, giving rise to higher device open circuit voltages and power conversion efficiencies exceeding 17%. A reduction in defect activation energy of over 30% calculated via admittance spectroscopy and confocal fluorescence intensity mapping indicates successful passivation of recombination/trap centers at grain boundaries. We speculate that guanidinium ions serve to suppress formation of iodide vacancies and passivate under-coordinated iodine species at grain boundaries and within the bulk through their hydrogen bonding capability. These results present a simple method for suppressing nonradiative carrier loss in hybrid perovskites to further improve performances toward highly efficient solar cells.

Stability and scalability have become the two main challenges for perovskite solar cells (PSCs) with the research focus in the field advancing toward commercialization. One of the prerequisites to solve these challenges is to develop a cost-effective, uniform, and high quality electron transport layer that is compatible with stable PSCs. Sputtering deposition is widely employed for large area deposition of high quality thin films in the industry. Here the composition, structure, and electronic properties of room temperature sputtered SnO2 are systematically studied. Ar and O-2 are used as the sputtering and reactive gas, respectively, and it is found that a highly oxidizing environment is essential for the formation of high quality SnO2 films. With the optimized structure, SnO2 films with high quality have been prepared. It is demonstrated that PSCs based on the sputtered SnO2 electron transport layer show an efficiency up to 20.2% (stabilized power output of 19.8%) and a T-80 operational lifetime of 625 h. Furthermore, the uniform and thin sputtered SnO2 film with high conductivity is promising for large area solar modules, which show efficiencies over 12% with an aperture area of 22.8 cm(2) fabricated on 5 x 5 cm(2) substrates (geometry fill factor = 91%), and a T-80 operational lifetime of 515 h.

In this work all-inorganic perovskite CsPbIBr2 are doped with Mn to compensate their shortcomings in band structure for the application of perovskite solar cells (PSCs). The novel Mn-doped all-inorganic perovskites, CsPb1-xMnxI1+2xBr2-2x, are prepared in ambient atmosphere. As the concentration of Mn2+ ions increases, the bandgaps of CsPb1-xMnxI1+2xBr2-2x decrease from 1.89 to 1.75 eV. Additionally, when the concentration of Mn dopants is appropriate, this novel Mn-doped all-inorganic perovskite film shows better crystallinity and morphology than its undoped counterpart. These advantages alleviate the energy loss in hole transfer and facilitate the charge-transfer in perovskites, therefore, PSCs based on these novel CsPb1-xMnxI1+2xBr2-2x perovskite films display better photovoltaic performance than the undoped CsPbIBr2 perovskite films. The reference CsPbIBr2 cell reaches a power conversion efficiency (PCE) of 6.14%, comparable with the previous reports. The CsPb1-xMnxI1+2xBr2-2x cells reach the highest PCE of 7.36% (when x= 0.005), an increase of 19.9% in PCE. Furthermore, the encapsulated CsPb0.995Mn0.005I1.01Br1.99 cells exhibit good stability in ambient atmosphere. The storage stability measurements on the encapsulated PSCs reveal that PCE is dropped by only 8% of the initial value after >300 h in ambient. Such improved efficiency and stability are achieved using low-cost carbon electrodes (without expensive hole transport materials and Au electrodes).

In this communication, we report an efficient and flexible perovskite solar cell based on formamidinium lead trihalide (FAPbI3) with simplified configuration. The device achieved a champion efficiency of 12.70%, utilizing direct contact between metallic indium tin oxide (ITO) electrode and perovskite absorber. The underlying working mechanism is proposed subsequently, via a systematic investigation focusing on the heterojunction within this device. A significant charge storage has been observed in the perovskite, which is believed to generate photovoltage and serves as the driving force for charge transferring from the absorber to ITO electrode as well. More importantly, this simplified device structure on flexible substrates suggests its compatibility for scale-up fabrication, which paves the way for commercialization of perovskite photovoltaic technology.

In this study, we communicate an investigation on efficient CH3NH3PbI3-based solar cells with carbon electrode using mesoporous TiO2 and NiO layers as electron and hole selective contacts. The device possesses an appreciated power conversion efficiency of 14.9% under AM 1.5G illumination. The detailed information can be disclosed with impedance spectroscopy via tuning the interfaces between CH3NH3PbI3 and different charge selective contacts. The results clearly show charge accumulation at the interface of CH3NH3PbI3. The NiO is believed to efficiently accelerate charge extraction to the external circuit. The extracted charge could improve photovoltaic performance by shifting hole Fermi level down, achieving a high device photovoltage. A fast interfacial recombination at the interface of CH3NH3PbI3/electron selective contact layer (mesoporous TiO2), occurring in millisecond domains, is the critical issue for charge carrier recombination loss.

Minimization of defects in absorber materials is essential for hybrid perovskite solar cells, especially when constructing thick polycrystalline layers in a planar configuration. Here, a simple methylamine solution-based additive is reported to improve film quality with nearly an order of magnitude reduction in intrinsic defect concentration. In the resultant film, an increase in carrier lifetime as a result of a decrease in shallow electronic disorder is observed. This superior crystalline film quality is further evidenced via a doubled spin relaxation time as compared with other reports. Bearing sufficient carrier diffusion length, a thick absorber layer (≈650 nm) is implemented in planar devices to achieve a champion power conversion efficiency of 20.02% with a stabilized output efficiency of 19.01% under one sun illumination. This work demonstrates a simple approach to improve hybrid perovskite film quality by substantial reduction of intrinsic defects for wide applications in optoelectronics.

We report on an experimental study of three organic push-pull dyes (coded as zzx-op1, zzx-op1-2, and zzx-op1-3) featuring one, two, and three fluorene units as spacers between donors and acceptors for p-type dye-sensitized solar cells (p-DSSC). The results show increasing the number of spacer units leads to obvious increases of the absorption intensity between 300 nm and 420 nm, a subtle increase in hole driving force, and almost the same hole injection rate from dyes to NiO nanoparticles. Under optimized conditions, the zzx-op1-2 dye with two fluorene spacer units outperforms other two dyes in p-DSSC. It exhibits an unprecedented photocurrent density of 7.57 mA cm(-2) under full sun illumination (simulated AM 1.5G light illumination, 100 mW cm(-2)) when the I(-)/I3(-) redox couple and commercial NiO nanoparticles were used as an electrolyte and a semiconductor, respectively. The cells exhibited excellent long-term stability. Theoretical calculations, impedance spectroscopy, and transient photovoltage decay measurements reveal that the zzx-op1-2 exhibits lower photocurrent losses, longer hole lifetime, and higher photogenerated hole density than zzx-op1 and zzx-op1-3. A dye packing model was proposed to reveal the impact of dye aggregation on the overall photovoltaic performance. Our results suggest that the structural engineering of organic dyes is important to enhance the photovoltaic performance of p-DSSC.