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Improvements to perovskite solar cells (PSCs) have focused on increasing their power conversion efficiency (PCE) and operational stability and maintaining high performance upon scale-up to module sizes. We report that replacing the commonly used mesoporous–titanium dioxide electron transport layer (ETL) with a thin layer of polyacrylic acid–stabilized tin(IV) oxide quantum dots (paa-QD-SnO 2 ) on the compact–titanium dioxide enhanced light capture and largely suppressed nonradiative recombination at the ETL–perovskite interface. The use of paa-QD-SnO 2 as electron-selective contact enabled PSCs (0.08 square centimeters) with a PCE of 25.7% (certified 25.4%) and high operational stability and facilitated the scale-up of the PSCs to larger areas. PCEs of 23.3, 21.7, and 20.6% were achieved for PSCs with active areas of 1, 20, and 64 square centimeters, respectively.

Lead (Pb) halide perovskite light-emitting diodes (PeLEDs) have demonstrated extraordinary optoelectronic performance. However, the toxicity of Pb has raised as a serious concern. Removing Pb from the best-performing PeLEDs without compromising their excellent external quantum efficiencies (EQEs) remains a challenge. Here we report a tautomeric mixture coordination-induced electron localization strategy to fundamentally stabilize Pb-free TEA2SnI4 (TEAI, 2-thiophenethylammonium iodide) perovskite by incorporating cyanuric acid (CA). We demonstrate that a crucial function of the coordination is to amplify electronic effects and even extend to Sn atoms without strong bonding with CA, due to the formation of H-bonded tautomeric dimer and trimer superstructures on the perovskite surface. This electron localization weakens adverse effects from Anderson localization and contributes to more ordered and stable crystal structure in the resultant TEA2SnI4, which synergistically improve the perovskite with two orders of magnitude reduction in nonradiative recombination capture coefficient and about 2-fold enhancement in exciton binding energy. Levering by the interactional profit, our target Pb-free PeLED demonstrated an EQE of up to 20.13 per cent, representing a performance comparable to that of state-of-the-art Pb-containing PeLEDs. We anticipate that these findings will provide insights into the stabilization of Sn(II) perovskites and inspire researchers to pioneer Pb-free perovskite applications.

Extensive studies of electron transport in Dirac materials have shown positive magneto-resistance (MR) and positive magneto-thermopower (MTP) in a magnetic field perpendicular to the excitation current or thermal gradient. In contrast, measurements of electron transport often show a negative longitudinal MR and negative MTP for a magnetic field oriented along the excitation current or thermal gradient; this is attributed to the chiral anomaly in Dirac materials. Here, we report a very different magneto-thermoelectric transport behavior in the massive Dirac material ZrTe5. Although thin flakes show a commonly observed positive MR in a perpendicular magnetic field, distinct from other Dirac materials, we observe a sharp negative MTP. In a parallel magnetic field, we still observe a negative longitudinal MR, however, a remarkable positive MTP is observed for the fields parallel to the thermal gradients. Our theoretical calculations suggest that this anomalous magneto-thermoelectric behavior can be attributed to the screened Coulomb scattering. This work demonstrates the significance of impurity scattering in the electron transport of topological materials and provides deep insight into the novel magneto-transport phenomena in Dirac materials.

Metal halide perovskites of the general formula ABX3—where A is a monovalent cation such as caesium, methylammonium or formamidinium; B is divalent lead, tin or germanium; and X is a halide anion—have shown great potential as light harvesters for thin-film photovoltaics1–5. Among a large number of compositions investigated, the cubic α-phase of formamidinium lead triiodide (FAPbI3) has emerged as the most promising semiconductor for highly efficient and stable perovskite solar cells6–9, and maximizing the performance of this material in such devices is of vital importance for the perovskite research community. Here we introduce an anion engineering concept that uses the pseudo-halide anion formate (HCOO−) to suppress anion-vacancy defects that are present at grain boundaries and at the surface of the perovskite films and to augment the crystallinity of the films. The resulting solar cell devices attain a power conversion efficiency of 25.6 per cent (certified 25.2 per cent), have long-term operational stability (450 hours) and show intense electroluminescence with external quantum efficiencies of more than 10 per cent. Our findings provide a direct route to eliminate the most abundant and deleterious lattice defects present in metal halide perovskites, providing a facile access to solution-processable films with improved optoelectronic performance. Incorporation of the pseudo-halide anion formate during the fabrication of α-FAPbI3 perovskite films eliminates deleterious iodide vacancies, yielding solar cell devices with a certified power conversion efficiency of 25.21 per cent and long-term operational stability.

Aiming at the problem that the traditional PID algorithm omits the nonlinear characteristics of the bridge crane system and the control effect is limited, this paper puts forward an energy coupling control strategy based on an adaptive fuzzy strategy. The coupling generalized semaphore for the Lyapunov controller is obtained by solving the dynamic equation of the bridge crane with energy, and the controller parameters are adjusted by using an adaptive fuzzy strategy. The simulation results show that the designed controller has a better anti-sway effect than the traditional PID controller.

Nanocrystalline tin (IV) oxide (SnO2) electron-transport layers (ETL) have shown great potential for achieving highly efficient, stable perovskite solar cells (PSCs), in particular low-temperature-processed flexible PSCs. Recently, studies have further shown that a modified SnO2 bottom layer facilitates the deposition of highly crystalline perovskite films, boosting the photovoltaic performance of the PSCs. The modulation of perovskite crystallization processes is a key to obtain highly crystalline and stable perovskite films; however, a fundamental understanding is still missing. Herein, we report an in situ synchrotron-based two-dimensional grazing-incidence X-ray diffraction technique to explore the SnO2 ETL-modulated perovskite crystallization kinetics for the first time. The titanium carbide (Ti3C2Tx)-MXene quantum dot-modified SnO2 (MQDs-SnO2) ETL was found to be able to rapidly induce perovskite nucleation from the precursor solution, forming an intermediate perovskite phase upon anti-solvent treatment. This substantially improves the crystal quality and phase stability of the as-fabricated perovskite film. Benefiting in addition from the superior charge extraction properties of the MQDs-SnO2 layer, a steady-state power conversion efficiency of up to 23.3%, as well as outstanding stability against humidity and light soaking was achieved for the corresponding PSCs.

Summary Interfacial modification is crucial to fully develop the potential of semiconductor devices, including the revolutionary halide perovskite-based optoelectronics, such as photovoltaics, light-emitting diodes, and photodetectors. The all-inorganic halide perovskites, which are potential long-term stable photovoltaic materials, are suffering from poor interfacial contact with metal oxide charge-selective layer, severely limiting the power conversion efficiency and stability of inorganic perovskite solar cells. Here, we propose an intermediate-phase engineering strategy to improve the inorganic perovskite/metal oxide interface by utilizing volatile salts. The introduction of organic cations (such as methylammonium and formamidinium), which can be doped into the perovskite lattice, leads to the formation of an organic-inorganic hybrid perovskite intermediate phase, promoting a robust interfacial contact through hydrogen bonding. A champion CsPb(I0.75Br0.25)3-based device with a power conversion efficiency of 17.0% and an open-circuit voltage of 1.34 V was realized, implying that a record of over 65% of the Shockley-Queisser efficiency limit is achieved.

The emergence and development of high-performance materials have benefited from the revolution in modern manufacturing technology, in which additive manufacturing (AM) is the most representative over the last four decades [...]

It is well established that the lack of understanding the crystallization process in two-step sequential deposition has a direct impact on efficiency, stability and reproducibility of perovskite solar cells. Here, we try to understand the solid-solid phase transition occuring during two-step sequential deposition of methylammonium lead iodide and formamidinium lead iodide. Using metadynamics, X-ray diffraction and Raman spectroscopy, we reveal the microscopic details of this process. We find that the formation of perovskite proceeds through intermediate structures and report polymorphs found for methylammonium lead iodide and formamidinium lead iodide. From simulations, we discover a possible crystallization pathway for the highly efficient metastable α-phase of formamidinium lead iodide. Guided by these simulations, we perform experiments that results in the room temperature crystallization of α-formamidinium lead iodide.

It is well established that the lack of understanding the crystallization process in two-step sequential deposition has a direct impact on efficiency, stability and reproducibility of perovskite solar cells. Here, we try to understand the solid-solid phase transition occuring during two-step sequential deposition of methylammonium lead iodide and formamidinium lead iodide. Using metadynamics, X-ray diffraction and Raman spectroscopy, we reveal the microscopic details of this process. We find that the formation of perovskite proceeds through intermediate structures and report polymorphs found for methylammonium lead iodide and formamidinium lead iodide. From simulations, we discover a possible crystallization pathway for the highly efficient metastable α-phase of formamidinium lead iodide. Guided by these simulations, we perform experiments that results in the room temperature crystallization of α-formamidinium lead iodide.

Moving a perovskite into the black The bandgap of the black α-phase FAPbI 3 (where FA is formamidinium) is nearly ideal for solar cells, but it is unstable with respect to the photoinactive yellow δ-phase. Lu et al. found that a film of the yellow phase was converted to a highly crystalline black phase by vapor exposure to methylammonium thiocyanate at 100°C, and it retained this structure after 500 hours at 85°C. Solar cells fabricated with this material had a power conversion efficiency of more than 23%. After 500 hours under maximum power tracking and a period of dark recovery, 94% of the original efficiency was retained. Science , this issue p. eabb8985

Metal halide perovskites of the general formula ABX

Mixtures of cations or halides with FAPbI

Power conversion efficiency (PCE) of the perovskite solar cells (PSCs) has remarkably been increased from 3.1% to 25.2%. The fast expansion of the PSCs has been along with the development of compositional and interface engineering, which has been playing a critical role. For the PSCs with record high-efficiency and stability, the perovskite absorber layer has been changed from the initial MAPbI3- to FAPbI3-based compositions. Owing to the enormous engineering works, perovskite absorber layers with monolithic grains could be achieved, in which the interior defects are negligible compared with the surface defects. Therefore, interface engineering, which can passivate the surface defects and/or isolate the perovskite from the environmental moistures, has been playing a more and more important role to further boost the PCE and stability of the PSCs. Herein, a compact review study of the compositional and interface engineering is presented and promising strategies and directions of the PSCs are discussed., Graphical Abstract, Highlights • Perovskite compositional engineering from MAPbI3 to FAPbI3 • Stabilization of α-FAPbI3 • Passivation strategies regarding different types of defects • Future perspectives of efficient and stable PSCs, Applied Chemistry; Materials Chemistry; Energy Materials

Organic-inorganic perovskite solar cells have attracted significant attention due to their remarkable performance. The use of alternative metal-oxide charge-transport layers is a strategy to improving device reliability for large-scale fabrication and long-term applications. Here, we report solution-processed perovskite solar cells employing nickel oxide hole-extraction layers produced in situ using an atmospheric pressure spatial atomic-layer deposition system, which is compatible with high-throughput processing of electronic devices from solution. Our sub-nanometer smooth (average roughness of ≤0.6 nm) oxide films enable the efficient collection of holes and the formation of perovskite absorbers with high electronic quality. Initial solar-cell experiments show a power-conversion efficiency of 17.1%, near-unity ideality factors, and a fill factor of >80% with negligible hysteresis. Transient measurements reveal that a key contributor to this performance is the reduced luminescence quenching trap density in the perovskite/nickel oxide structure.

Both a favorable material and designed structure are essential for a high-performance photodetector. For the excellent physical properties of organolead trihalide perovskites, with CH3NH3PbI3 films serving as a base layer, a bipolar heterojunction phototransistor-type perovskite photodetector is proposed. Benefiting from this bipolar heterojunction structure, which is characterized by high gain and low work voltage, an optimized device exhibits high performance with a photoresponsivity of 125 AW−1 and an external efficiency of 3.62 × 104% at 427 nm with a low work voltage of 0.7 V. Additionally, such phototransistors have a broad photoresponsivity from 360 to 820 nm. These results demonstrate that the bipolar heterojunction phototransistor, which is widely used in inorganic materials, is a promising structure for organolead trihalide perovskite optoelectronic devices, paving a new way for developing high-performance photodetectors.

The purpose of this research was to understand the effect of a built-in ferroelectric field on the performance of two-dimensional (2D) lead-free perovskite material-based phototransistor applications. In this work, ferroelectric polymer poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) and two-dimensional (2D) lead-free perovskite ((C6H5C2H4NH3)2SnI4) were utilized as a dielectric layer and a channel layer, respectively. We observed that large hysteresis was successfully eliminated in the transfer curve, as well as the subthreshold swing being significantly reduced by one order of magnitude after P(VDF-TrFE) was introduced as a dielectric layer. Under polarization “up” and “down” states, the device achieved a high photo-switching on/off ratio (>100) and a short photoresponse time (50 ms), respectively. In addition to that, the device also demonstrated a high responsivity of 14.57 A W−1 and a high detectivity of 1.74 × 1012 Jones under the polarization “up” state with an illumination intensity of 21 μW cm−2. In addition, low temperature solution-processed P(VDF-TrFE) and (C6H5C2H4NH3)2SnI4 (except for the contacts of Au electrodes) in this work are considered to be suitable and compatible for flexible-based phototransistor applications in the future.

Potassium halides have recently garnered much attention, due to their improvement of perovskite solar cell performance. A small amount of potassium halide incorporated in a perovskite absorber is able to provide advantages in terms of crystallinity, light absorption and trap state reduction. Here, we present a potassium chloride (KCl) pretreatment process to fabricate high-efficiency perovskite solar cells (PSCs). A KCl layer was inserted at the SnO2/MAPbI3−xClx interface via a simple spin coating method. It is observed that potassium cations (K+) and chloride anions (Cl−) diffused into the perovskite film during the thermal annealing process. The diffusion of K+ and Cl− will stop when they reach a bulk defect, resulting in an active passivation effect. It is verified that the incorporation of KCl enhances the crystal perfection and light absorption of the perovskite film. The average power conversion efficiency (PCE) of PSCs increases from 16.62% to 17.81%, with a leading PCE of 19.44%.

Smart classrooms attach great importance to autonomy, investigation, thoughts, and diversity. Therefore, smart mathematics teaching is influenced by smart education claims that the teaching activities are carried out aided by information technology and advocates students solve problems through innovative cooperation learning. As a result, creating a student-oriented and teacher-directed teaching model highlights the student’s dominant position. The mathematics smart classroom evaluation in elementary school is an in-depth analysis of the pupil’s cognitive characteristics and wisdom class essence. This article actively explores the standards for teaching design and implementation through the evaluation of smart mathematics classrooms. It preliminarily draws up an evaluation scale to make the first-step explorations for future elementary school math smart classroom design.

It is well established that the lack of understanding the crystallization process in a two-step sequential deposition has a direct impact on efficiency, stability, and reproducibility of perovskite solar cells. Here, we try to understand the solid-solid phase transition occurring during the two-step sequential deposition of methylammonium lead iodide and formamidinium lead iodide. Using metadynamics, x-ray diffraction, and Raman spectroscopy, we reveal the microscopic details of this process. We find that the formation of perovskite proceeds through intermediate structures and report polymorphs found for methylammonium lead iodide and formamidinium lead iodide. From simulations, we discover a possible crystallization pathway for the highly efficient metastable α phase of formamidinium lead iodide. Guided by these simulations, we perform experiments that result in the low-temperature crystallization of phase-pure α-formamidinium lead iodide., Science Advances, 7 (17), ISSN:2375-2548

Here, we present the deposition of antimony-doped tin oxide thin films using the ambient spray pyrolysis technique and demonstrate their implementation as transparent electrodes (anodes) in red, green and blue organic light emitting diodes. The films were spray coated at 380 °C from SnCl4 and SbCl3 solution blends in methanol and ∼230 nm thick films were investigated by means of X-ray diffraction, AFM, UV-Vis absorption spectroscopy, 4-point probe, Hall effect measurements and Kelvin probe. It was found that for optimum antimony doping in the precursor solution of ∼2 wt%, the as-deposited ATO films exhibit excellent characteristics such as a low surface roughness (RRMS) of ∼ 6.3 nm, a high work function (∼−5.03 eV), a wide direct band gap (∼4.2 eV), high transparency in the visible spectrum in excess of 85% on glass, a low sheet resistivity (∼32 Ohms sq−1), a high charge carrier concentration (∼6.35 × 1020 cm−3) and a carrier mobility of ∼32 cm2 V−1 s−1. Furthermore, the electrical and optical performance i.e. the turn on voltage and external quantum efficiency of red, green and blue OLEDs fabricated on optimized SnO2:Sb films were identical to those of OLEDs fabricated on commercially available ITO (Rs ∼ 15 Ohms sq−1) and were found to be in excess of 11%, 0.3% and 13% for red, green and blue OLEDs, respectively.

Multimodal nanoparticulate materials are described, offering magnetic, radionuclide, and fluorescent imaging capabilities to exploit the complementary advantages of magnetic resonance imaging (MRI), positron emission tomography/single-photon emission commuted tomography (PET/SPECT), and optical imaging. They comprise Fe3O4@NaYF4 core/shell nanoparticles (NPs) with different cation dopants in the shell or core, including Co0.16Fe2.84O4@NaYF4(Yb, Er) and Fe3O4@NaYF4(Yb, Tm). These NPs are stabilized by bisphosphonate polyethylene glycol conjugates (BP-PEG), and then show a high transverse relaxivity (r2) up to 326 mM(-1) s(-1) at 3T, a high affinity to [(18)F]-fluoride or radiometal-bisphosphonate conjugates (e.g., (64)Cu and (99m)Tc), and fluorescent emissions from 500 to 800 nm under excitation at 980 nm. The biodistribution of intravenously administered particles determined by PET/MR imaging suggests that negatively charged Co0.16Fe2.84O4@NaYF4(Yb, Er)-BP-PEG (10K) NPs cleared from the blood pool more slowly than positively charged NPs Fe3O4@NaYF4(Yb, Tm)-BP-PEG (2K). Preliminary results in sentinel lymph node imaging in mice indicate the advantages of multimodal imaging.

We compare the current density–voltage (J–V) and magnetoconductance (MC) response of a poly(3-hexyl-thiophene) (P3HT) device (Au/P3HT(350 nm)/Al) before and after annealing above the glass transition temperature of 150 °C under vacuum. There is a decrease of more than 3 orders of magnitude in current density due to an increase of the charge injection barriers after de-doping through annealing. An increase, approaching 1 order of magnitude, in the negative MC response after annealing can be explained by a shift in the Fermi level due to de-doping, according to the bipolaron mechanism. We successfully tune the charge injection barrier through re-doping by photo-oxidation. This leads to the charge injection and transport transitioning from unipolar to ambipolar, as the bias increases, and we model the MC response using a combination of bipolaron and triplet-polaron interaction mechanisms.

Topological Kondo insulators (TKIs) are a new class of topological materials in which topological surface states dominate the transport properties at low temperatures. They are also an ideal platform for studying the interplay between strong electron correlations and topological order. Here, hysteretic magnetoresistance (MR) is observed in TKI SmB6 thin nanowires at temperatures up to 8 K, revealing the strong magnetism at the surface of SmB6. It is also found that such MR anomaly exhibits an intriguing finite size effect and only appears in nanowires with diameter smaller than 58 nm. These nontrivial phenomena are discussed in terms of the latest Kondo breakdown model, which incorporates the RKKY magnetic interaction mediated by surface states with the strong electron correlation in SmB6. It would provide new insight into the nature of TKI surface states. Additionally, a non‐monotonically temperature dependent positive magnetoresistance is observed at intermediate temperatures, suggesting the possible impurity‐band conduction in SmB6, other than the surface state transport at low temperatures and the bulk‐band transport at high temperatures.

One-step solution process is the simplest method to fabricate organic-inorganic metal halide perovskite thin films, which however does not work well when employed in the planar-heterojunction (PHJ) solar cells due to the generally poor film morphology. Here we show that hydrazinium chloride can be used as an additive in the precursor solution to produce perovskite films featuring higher coverage and better crystallinity. The light absorption ability and charge carrier lifetime are both significantly improved accordingly. Under the optimal additive ratio, the average power conversion efficiency (PCE) of the inverted PHJ perovskite solar cells greatly increases by as much as 70%, and the champion device shows a satisfying PCE of 12.66%. These results suggest that N2H5Cl is a promising additive for fabricating high-efficiency perovskite solar cells via one-step method, which could be of interest in the future commercial solar cell industry. ispartof: Acs Applied Materials & Interfaces vol:9 issue:42 pages:36810-36816 ispartof: location:United States status: published

Infra-red emission (980 nm) of sub 10 nm Yb3+-doped NaYF4 nanoparticles has been sensitized through the excitation of 2-hydroxyperfluoroanthraquinone chromophore (1,2,3,4,5,6,7-heptafluro-8-hydroxyanthracene-9,10-dione) functionalizing the nanoparticle surface. The sensitization is achieved with a broad range of visible light excitation (400–600 nm). The overall near infra-red (NIR) emission intensity of Yb3+ ions is increased by a factor 300 as a result of the broad and strong absorption of the chromophore compared with ytterbium’s intrinsic absorption. Besides the Yb3+ NIR emission, the hybrid composite shows organic chromophore-based visible emission in the orange-red region of the spectrum. We observe the energy migration process from the sensitized Yb3+ ions at the surface to those in the core of the particle using time-resolved optical spectroscopy. This highlights that the local environments for emitting Yb3+ ions at the surface and center of the nanoparticle are not identical, which causes important differences in the NIR emission dynamics. Based on the understanding of these processes, we suggest a simple strategy to control and modulate the decay time of the functionalized Yb3+-doped nanoparticles over a relatively large range by changing physical or chemical parameters in this model system.

Recently, perovskite based solar cells have attracted lots of research interest, some of which is in the passivation of perovskite surfaces, particularly the heterojunction based surface passivation. In this study, the optical dynamics of MAPbBr

Topological insulators are insulating in the bulk but possess spin-momentum locked metallic surface states protected by time-reversal symmetry. The existence of these surface states has been confirmed by angle-resolved photoemission spectroscopy (ARPES) and scanning tunneling microscopy (STM). Detecting these surface states by transport measurement, which might at first appear to be the most direct avenue, was shown to be much more challenging than expected. Here, we report a detailed electronic transport study in high quality Bi2Se3 topological insulator thin films. Measurements under in-plane magnetic field, along and perpendicular to the bias current show opposite magnetoresistance. We argue that this contrasting behavior is related to the locking of the spin and current direction providing evidence for helical spin structure of the topological surface states.

The photoluminescence (PL) variations of organic-inorganic hybrid lead halide perovskites in different atmospheres are well documented, while the fundamental mechanism still lacks comprehensive understandings. This study reports the reversible optical and electrical properties of methylammonium lead bromide (MAPbBr3 or CH3NH3PbBr3) single crystals caused by air infiltration. With the change in the surrounding atmosphere from air to vacuum, the PL intensity of perovskite single crystals decreases, while the conductivity increases. By means of first-principles computational studies, the shallow trap states are considered as key elements in PL and conductivity changes. These results have important implications for the characterization and application of organic-inorganic hybrid lead halide perovskites in vacuum.

In this paper, a series of Er(3+)-doped Y2O3 samples are systematically investigated, focusing on the effect of the doping concentration on the emission lifetime and spectrum under both 488 nm and 980 nm excitations. Decay times of the (4)S3/2 and (4)F9/2 emitting states under 488 nm and 980 nm excitations are found to be different and concentration dependent. We explain these variations in terms of the changes in the up-conversion routes caused by the predominance of energy exchanges that involve the lowest lying excited states.

We have used the introduction of shallow hole traps in poly(3-hexyl-thiophene) to test one of the predictions of the bipolaron theory of magnetoconductance (MC). The results show that the introduction of shallow traps effectively increases the degree of energetic disorder in the transport states whilst not affecting the position of the Fermi level and that this results in an increase in the MC response. These results are demonstrated to be in qualitative agreement with the theory and suggest one mechanism through which trap states may affect the MC response of organic semiconductors. This work presents a controllable way of chemical doping to engineer a change in absolute current at a given bias depending on the choice of anodes. It also allows for tuning the magnitude of negative MC response and electroluminescence efficiency under different driving conditions.

Interfacial modification is crucial to fully develop the potential of semiconductor devices, including the revolutionary halide perovskite-based optoelectronics, such as photovoltaics, light-emitting diodes, and photodetectors. The all-inorganic halide perovskites, which are potential long-term stable photovoltaic materials, are suffering from poor interfacial contact with metal oxide charge-selective layer, severely limiting the power conversion efficiency and stability of inorganic perovskite solar cells. Here, we propose an intermediate-phase engineering strategy to improve the inorganic perovskite/metal oxide interface by utilizing volatile salts. The introduction of organic cations (such as methylammonium and formamidinium), which can be doped into the perovskite lattice, leads to the formation of an organic-inorganic hybrid perovskite intermediate phase, promoting a robust interfacial contact through hydrogen bonding. A champion CsPb(I0.75Br0.25)(3)-based device with a power conversion efficiency of 17.0% and an open-circuit voltage of 1.34 V was realized, implying that a record of over 65% of the Shockley-Queisser efficiency limit is achieved.