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The use of transparent conducting oxide (TCO) as a substrate in Cu2ZnSn(S,Se)4 (CZTSSe) thin-film solar cells allows for advanced applications, such as bifacial, semi-transparent, and tandem solar cells with the capability to increase power density generation. However, the efficiency of this kind of solar cell is still below 6% based on the low-cost solution process. In this work, we develop a composition gradient strategy and demonstrate a 6.82% efficient CZTSSe solar cell on F:SnO2 (FTO) substrate under the ambient condition. The composition gradient is realized by simply depositing the precursor inks with different Zn/Sn ratios. To verify that the high performance of the solar cell is attributed to the composition gradient strategy rather than the sole change of the Zn/Sn ratio, devices based on absorbers with varied Zn/Sn ratios are fabricated. Furthermore, the structure and surface morphology of the CZTSSe films with/without composition gradients are examined. The presence of elemental gradient through the depth of the CZTSSe films before and after annealing is confirmed by secondary ion mass spectroscopy analysis. It is found that the composition gradient enhances the crystallinity of the absorber, reduces the surface roughness as well as device parasitic losses, contributing to a higher fill factor, open-circuit voltage and conversion efficiency.

In the past decades, the inverted structure (p‐i‐n structure) perovskite solar cells (PVSCs) have been attracted more by the researchers owing to their ease of fabrication, cost‐effectiveness, lower processing temperature for the fabrication of large scale and flexible devices with negligible J−V hysteresis effects. The hole transporting layer (HTL) as a major served content of PVSCs has significant influence on light harvesting, carrier extraction and transportation, perovskite crystallization, stability and cost. Generally, the organic materials are used as HTLs which have less stability due to their morphology under thermal conditions; thus, leads to change in properties of them. A tantalizing possibility is replacement of p‐type inorganic materials instead of organic materials but the plenty of options are available for inorganic HTLs. However, the development of more variants for inorganic HTL is a major challenge. Till date, many materials have been reported, but their performances have not superseded that of their organic counterparts. Herein, the review on various inorganic HTLs based inverted PVSCs has been reported and analyzed their performances with appropriate properties such as proper energy level and high carrier mobility which are not only assisted with charge transport, but also improved the stability of PVSCs under ambient conditions.

Electronic defects at grain boundaries and surfaces of perovskite crystals impair the photovoltaic performance and stability of solar devices. In this work, we report the compensation of photovoltage losses in blade-coated methylammonium lead triiodide (MAPbI3) devices via passivation with natural amino acid (NAA) molecules. We found that the optoelectronic properties of NAA-passivated perovskite films and the corresponding device performances are closely correlated with the molecular interaction strength. A side-by-side comparative study of four typical NAAs reveals that arginine (Arg) functionalized with a guanidine end group exhibits optimum passivation effects owing to the strongest coordinative bonding with the uncoordinated Pb2+, which markedly suppresses the detrimental antisite PbI deep level defects. As a result, nonradiative charge recombination is significantly reduced, resulting in a substantially increased open-circuit voltage (VOC) of 1.17 V and a high efficiency of 20.49%. A solar module with an active area of 10.08 cm2 is also fabricated, yielding an efficiency of 15.65% with negligible VOC losses. In parallel, the Arg-passivated solar devices exhibit enhanced operational stability due to the formation of a hydrophilic Arg protective layer which encapsulates the perovskite crystals.

Ambient air atmosphere is inimical to organic–inorganic halide perovskites and organic hole transport materials, and is, thus, necessarily avoided during device fabrication. To solve this issue, it is highly desirable to design stable perovskite-based composites and device configurations. Here, fully ambient-air and antisolvent-free-processed, stable and all-inorganic metal-oxide selective contact hole-conductor-free perovskite solar cells (HCF-PSCs) based on perovskite-based composites with an interfacial engineering strategy are reported. The formation of perovskite-based composites by interfacial engineering with carbon–graphite–CuδNi1−δO not only improved interfacial contacts, charge extraction and transport but also passivated trap states of perovskite thin films and charge recombination at the interfaces. Thus, such perovskite composites with interfacial engineering-based HCF-PSCs without encapsulation showed excellent stability by sustaining 94% of initial PCE over 300 days under ambient conditions.

Carrier loss mechanisms at microscopic regions is imperative for high-performance polycrystalline inorganic thin-film solar cells. Despite the progress on Kesterite, a promising environmental-benign and earth-abundant thin-film photovoltaic material, the microscopic carrier loss mechanisms and their impact on device performance remain unknown. Herein, we unveil these mechanisms in state-of-the-art Cu2ZnSnSe4 (CZTSe) solar cells using a framework that links microscopic-structural and optoelectronic characterizations with three-dimensional device simulations. The results indicate the CZTSe films have an encouraging intragrain minority carrier lifetime of >10 ns, a marginal radiative recombination loss through sub-band recombination and electrostatic potential fluctuation, whilst a large effective grain boundary recombination velocity of around 104 cm s-1 and a low net carrier density of ~1×1015 cm-3. We identify that severe grain boundary recombination and low net carrier density are the current limiting factors of device performance. The established framework can greatly advance the research of kesterite and other emerging photovoltaic materials.

Antimony selenide (Sb2Se3) nanorod arrays along the [001] orientation are known to transfer photogenerated carriers rapidly due to the strongly anisotropic one‐dimensional crystal structure. With advanced light‐trapping structures, the Sb2Se3 nanorod array‐based solar cells have excellent broad spectral response properties, and higher short‐circuit current density than the conventional planar structured thin film solar cells. However, the interface engineering for the Sb2Se3 nanorod array‐based solar cell is more crucial to increase the performance, because it is challenging to coat a compact buffer layer with perfect coverage to form a uniform heterojunction interface due to its large surface area and length–diameter ratio. In this work, an intermeshing In2S3 nanosheet‐CdS composite as the buffer layer, compactly coating on the Sb2Se3 nanorod surface is constructed. The application of In2S3‐CdS composite buffers build a gradient conduction band energy configuration in the Sb2Se3/buffer heterojunction interface, which reduces the interface recombination and enhances the transfer and collection of photogenerated electrons. The energy‐level regulation minimizes the open‐circuit voltage deficit at the interfaces of buffer/Sb2Se3 and buffer/ZnO layers in the Sb2Se3 solar cells. Consequently, the Sb2Se3 nanorod array solar cell based on In2S3‐CdS composite buffers achieves an efficiency of as high as 9.19% with a V OC of 461 mV., An intermeshing In2S3 nanosheet‐CdS composite buffer layer is constructed and applied in Sb2Se3 nanorod array solar cells, which build a gradient conduction band energy configuration in the Sb2Se3/buffer heterojunction interface. The champion cell based on In2S3‐CdS composite buffers achieves a PCE of 9.19% with an V OC of as high as 461 mV.

Antimony selenide (Sb2Se3) has a one-dimensional (1D) crystal structure comprising of covalently bonded (Sb4Se6)n ribbons stacking together through van der Waals force. This special structure results in anisotropic optical and electrical properties. Currently, the photovoltaic device performance is dominated by the grain orientation in the Sb2Se3 thin film absorbers. Effective approaches to enhance the carrier collection and overall power-conversion efficiency are urgently required. Here, we report the construction of Sb2Se3 solar cells with high-quality Sb2Se3 nanorod arrays absorber along the [001] direction, which is beneficial for sun-light absorption and charge carrier extraction. An efficiency of 9.2%, which is the highest value reported so far for this type of solar cells, is achieved by junction interface engineering. Our cell design provides an approach to further improve the efficiency of Sb2Se3-based solar cells., Antimony selenide is a promising thin film solar cell absorber material in which grain orientation is crucial for high device performance. Here Li et al. grow the material in nanorod arrays along the [001] direction and obtain record high efficiency of 9.2%.

In this study, the nickel oxide (NiOX) thin films were reactively sputtered at different working pressures in the oxide mode zone for application in flexible all-thin-film electrochromic devices (ATF-ECDs). The working pressure plays an important role on the various properties of the reactively sputtered NiOX thin film including the deposition rate, grain structure (microstructure), morphology, chemical composition, optical properties and electrochemical properties. The flexible ATF-ECDs with ≥2 Pa NiOX thin films perform high optical modulation and relatively fast response time during the electrochromic processes. The detailed electrochromic mechanism is discussed.

Ambient air atmosphere is inimical to organic-inorganic halide perovskites and organic hole transport materials, and is, thus, necessarily avoided during device fabrication. To solve this issue, it is highly desirable to design stable perovskite-based composites and device configurations. Here, fully ambient-air and antisolvent-free-processed, stable and all-inorganic metal-oxide selective contact hole-conductor-free perovskite solar cells (HCF-PSCs) based on perovskite-based composites with an interfacial engineering strategy are reported. The formation of perovskite-based composites by interfacial engineering with carbon-graphite-Cu

Environmentally benign and potentially cost‐effective Sb2Se3 solar cells have drawn much attention by continuously achieving new efficiency records. This article reports a compatible strategy to enhance the efficiency of planar n–i–p Sb2Se3 solar cells through Sb2Se3 surface modification and an architecture with oriented 1D van der Waals material, trigonal selenium (t‐Se). A seed layer assisted successive close spaced sublimation (CSS) is developed to fabricate highly crystalline Sb2Se3 absorbers. It is found that the Sb2Se3 absorber exhibits a Se‐deficient surface and negative surface band bending. Reactive Se is innovatively introduced to compensate the surface Se deficiency and form an (101) oriented 1D t‐Se interlayer. The p‐type t‐Se layer promotes a favored band alignment and band bending at the Sb2Se3/t‐Se interface, and functionally works as a surface passivation and hole transport material, which significantly suppresses interface recombination and enhances carrier extraction efficiency. An efficiency of 7.45% is obtained in a planar Sb2Se3 solar cell in superstrate n–i–p configuration, which is the highest efficiency for planar Sb2Se3 solar cells prepared by CSS. The all‐inorganic Sb2Se3 solar cell with t‐Se shows superb stability, retaining ≈98% of the initial efficiency after 40 days storage in open air without encapsulation.

As perovskite solar cells (PSCs) are highly efficient, demonstration of high-performance printed devices becomes important. 2D/3D heterostructures have recently emerged as an attractive way to relieving the film inhomogeneity and instability in perovskite devices. In this work, a 2D/3D ensemble with 2D perovskites self-assembled atop 3D methylammonium lead triiodide (MAPbI(3)) via a one-step printing process is shown. A clean and flat interface is observed in the 2D/3D bilayer heterostructure for the first time. The 2D perovskite capping layer significantly suppresses nonradiative charge recombination, resulting in a marked increase in open-circuit voltage (V-OC) of the devices by up to 100 mV. An ultrahigh V-OC of 1.20 V is achieved for MAPbI(3) PSCs, corresponding to 91% of the Shockley-Queisser limit. Moreover, notable enhancement in light, thermal, and moisture stability is obtained as a result of the protective barrier of the 2D perovskites. These results suggest a viable approach for scalable fabrication of highly efficient perovskite solar cells with enhanced environmental stability.

As perovskite solar cells are highly efficient and already meet the efficiency requirement for renewable power generation, more attention is given to technological barriers such as scalability and stability. In particular, the large efficiency losses associated with upscaling lab-scale devices to large-area modules represents one of the major hurdles for commercialization. Given the essential role of the perovskite films in the device performance, it is of critical importance to develop reliable crystallization protocols to deposit high-quality perovskite layers via scalable methods. This review summarizes recent advances in emerging crystallization protocols for the large-scale deposition of perovskite thin films. The unique merits of the well-developed crystallization strategies, including antisolvent, gas quenching, vacuum quenching, etc., are carefully analyzed and discussed. We highlight that, independent of the coating method, creating intermediate phases to decouple the otherwise overlapped solution coating and crystal growth is essential to realize homogeneous coatings of perovskite thin films. Strategies for enhancing the crystal morphology of perovskite films are presented as well, which is vitally important to realize reproducible manufacturing of large-area modules. This tutorial review assists the screening and development of robust crystallization strategies for scalable deposition of high-quality perovskite films for photovoltaic applications.

Two-dimensional perovskites have attracted substantial attention for solar cell applications because of their higher stability as compared to their 3D analogs. To achieve efficient charge transport in thin-film devices, obtaining high crystalline perovskite crystals perpendicularly aligned to the substrate is of great importance. This article reports the scalable printing of high-quality Dion–Jacobson (DJ) perovskite thin films via tailoring crystallization kinetics. Introducing a small amount of 1-methyl-2-pyrrolidinone to the conventional N,N-dimethylformamide:dimethyl sulfoxide-based precursor, the strong coordination with ammonium spacers enables a notably retarded crystallization, which results in perovskite films with distinctly enhanced crystallinity, highly vertical orientation, and graded phase distribution. Accordingly, efficient charge generation and ultrafast interphase charge transfer are realized. The champion DJ perovskite device delivers a high current density of 17.10 mA cm–2, an impressive open-circuit voltage of 1.21 V, leading to a stabilized efficiency of 16.19%. In addition, the devices processed from the ternary solvent exhibit remarkably improved stability under stimuli with light, heat, and humidity, benefiting from their superb phase stability. This work demonstrates an important advancement in scalable deposition of DJ perovskite thin films for efficient and stable photovoltaic devices.

Recent progress in perovskite photovoltaics has witnessed a growing interest in formamidinium lead iodide (FAPbI3), primarily due to its high efficiency potential and excellent stability. However, the high energy barrier of δ-to-α phase transition presents a major hurdle to fabricate phase-pure α-FAPbI3 layers. Here, we report a two-step phase transition process to deposit high-quality photovoltaic α-FAPbI3 films by printing method. This is realized by judicious selection of a Lewis base N-methyl-2-pyrrolidone (NMP) and its counter Lewis acid, which enables the regulation of intermediary phase to reduce the energy barrier. With fine tuning the phase transition pathway, phase-pure and stable α-FAPbI3 perovskite films are obtained, which yield solar devices with a champion efficiency of 21.35%. The printed mini-modules with active areas of 12.32 cm2 and 55.44 cm2 are also fabricated, giving efficiencies of 17.07% and 14.17%, respectively. This work provides new insights of α-FAPbI3 crystallization for constructing efficient and stable printed photovoltaic devices.

The tantalum pentoxide (Ta2O5) thin films used as protonic conductive solid electrolyte layers (SELs) in all thin film electrochromic devices (ATF-ECDs) were widely investigated. The working pressure played a great role in the microstructure and proton transfer of the Ta2O5 thin films. The Ta2O5 thin films were deposited by direct current (DC) reactive magnetron sputtering at different working pressures and growth mechanism was studied. The optical properties, structural properties, chemical compositions, morphologies and protonic conductive properties of the Ta2O5 thin films were systematically investigated. Moreover, the electrochromic properties for corresponding ATF-ECDs with Ta2O5 SELs were studied as well. The ATF-ECD with a 2.0 Pa Ta2O5 SEL exhibited the best device performance with high optical modulation and fast switch speeds.

The Sn-based perovskite solar cells (PSCs) provide the possibility that swaps the Pb element toward toxic-free PSCs. Here, we innovatively employed a molecular self-assembly approach to obtain a series CH3NH3Pb(1−x)SnxI3 (0≤x≤1) perovskite thin films with full coverage. The optimized planar CH3NH3Pb0.75Sn0.25I3 PSCs with inverted structure was consequently realized with a maximum power conversion efficiency (PCE) over 14 %, which displayed a stabilized power output (SPO) over 12 % within 200 s at 0.6 V forward bias. Afterward, we investigated the factors that limited the efficiency improvement of hybrid Sn-Pb PSCs, and analyzed the possible reason of the hysteresis effect occurred even in the inverted structure cell. Particularly, the oxidation of hybrid Sn-Pb perovskite thin film was demonstrated to be the main reason that caused the decreasing of minority-carrier lifetime, which quenched the carrier collection efficiency while the depletion layer was widened. The imbalance of charge transport was intensified that was associated with the increased hole defect-state density and decreased the electron defect-state density after Sn was introduced. This study is benefit to tackle the intractable issue regarding the toxic Pb in perovskite devices and step forward toward realizing the lead-free PSCs with high stability and efficiency.

Crystallization of glass/Aluminum (50, 100, 200 nm) /hydrogenated amorphous silicon (a-Si:H) (50, 100, 200 nm) samples by Aluminum-induced crystallization (AIC) is investigated in this article. After annealing and wet etching, we found that the continuity of the polycrystalline silicon (poly-Si) thin films was strongly dependent on the double layer thicknesses. Increasing the a-Si:H/Al layer thickness ratio would improve the film microcosmic continuity. However, too thick Si layer might cause convex or peeling off during annealing. Scanning electron microscopy (SEM) and Energy Dispersive X-ray spectroscopy (EDX) are introduced to analyze the process of the peeling off. When the thickness ratio of a-Si:H/Al layer is around 1 to 1.5 and a-Si:H layer is less than 200 nm, the poly-Si film has a good continuity. Hall measurements are introduced to determine the electrical properties. Raman spectroscopy and X-ray diffraction (XRD) results show that the poly-Si film is completely crystallized and has a preferential (111) orientation.

Chemical doping has emerged as a favourable method for tuning the electrical properties of the hole-transport layer (HTL) in perovskite solar cells. Herein, we demonstrated an efficient dopant, cobalt(III) complex tris[2-((1H-pyrazol-1-yl)-4-tert-butylpyridine)cobalt(III)tris(bis(trifluoromethylsulfonyl)imide)] (FK209), which exhibited concentration distribution characteristics. The interfacial charge collection is demonstrated to be enhanced. We obtained the optimal power conversion efficiency (PCE) of 17.34% by optimizing the Co-complex doping ratio. Moreover, we found that the doping of Co-complex into the HTL significantly improved the stability under a sensitive atmosphere.

Metal halide perovskite solar cells (PSCs) have raised considerable scientific interest due to their high cost‐efficiency potential for photovoltaic solar energy conversion. As PSCs already are meeting the efficiency requirements for renewable power generation, more attention is given to further technological barriers as environmental stability and reliability. However, the most major obstacle limiting commercialization of PSCs is the lack of a reliable and scalable process for thin film production. Here, a generic crystallization strategy that allows the controlled growth of highly qualitative perovskite films via a one‐step blade coating is reported. Through rational ink formulation in combination with a facile vacuum‐assisted precrystallization strategy, it is possible to produce dense and uniform perovskite films with high crystallinity on large areas. The universal application of the method is demonstrated at the hand of three typical perovskite compositions with different band gaps. P‐i‐n perovskite solar cells show fill factors up to 80%, underpinning the statement of the importance of controlling crystallization dynamics. The methodology provides important progress toward the realization of cost‐effective large‐area perovskite solar cells for practical applications.

Sb2S3 has attracted great research interest very recently as a promising absorber material for photoelectric and photovoltaic devices because of its unique optical and electrical properties and single, stable phase. However, the intrinsic high resistivity property of Sb2S3 material is one of the major factors restricting the further improvement of its application. In this work, the C60 modification of Sb2S3 thin films is investigated. The conductivity of Sb2S3 thin films increases from 4.71 × 10−9 S cm−1 for unmodified condition to 2.86 × 10−8 S cm−1 for modified thin films. Thin‐film solar cells in the configuration of glass/(SnO2:F) FTO/TiO2/Sb2S3(C60)/Spiro‐OMeTAD/Au are fabricated, and the conversion efficiency is increased from 1.10% to 1.74%.

Metal halide perovskites have exhibited excellent properties as absorbers in solar cells, but this may simply be the first of many applications for this intriguing class of materials. Here, we report the nonlinear optical response of triiodide (CH3NH3PbI3) and mixed halide (CH3NH3PbI3–xClx) perovskite absorbers. The results show that they have large nonlinear refractive index (NRI), 3 orders of magnitude larger than that of silicon. Particularly, the NRI of CH3NH3PbI3–xClx is more than two times larger compared to that of CH3NH3PbI3. Meanwhile, both of them have been proven to possess saturable absorption effects with small nonlinear absorption coefficients which indicate that they can maintain excellent absorption under high-intensity irradiation and are favorable to modulators toward large-energy pulsed laser. Taking into consideration the saturable absorption effect, we demonstrated a pulsed laser with the perovskite as a pulse modulator. These results above indicate the potential for perovskites to be...

CuInS2 quantum dot (CIS QD)-sensitized solar cells (QDSSCs) with spiro-OMeTAD as the solid-state hole transport material were fabricated by using a successive ionic layer adsorption and reaction (SILAR) process. The structural, morphological, optical and photovoltaic characterizations of the composite films indicate the importance of thermal treatment in enhancing the performance of the solar cells. The results reveal that chalcopyrite CIS QDs of around 8 nm in size are distributed homogeneously over the surface of TiO2 particles and are well separated from each other under the proper annealing conditions. With increasing the temperature, the effect of annealing is to shift the absorption onset to longer wavelengths, thus improving the photocurrent substantially. It is also noteworthy that the annealing is beneficial for the efficient charge transport and the decreased charge recombination. Under simulated illumination (AM 1.5, 100 mW cm−2), the solid-state QDSSCs with distinct architectures deliver a maximum efficiency of 1.41% for the solar cell fabricated with a pristine CIS QD-sensitized TiO2 photoelectrode annealed up to 450 °C.

The Ag alloying Cu2ZnSnSe4 absorber has profound influences on the material properties including the carrier density, defects, grain structure and morphology, etc. It is found that Ag alloying could effective decrease the carrier density of Ag alloyed (Ag,Cu)2ZnSnSe4 (ACZTSe) absorbers and thus increase the depletion region width (DRW) of corresponding kesterite solar cells. At the same time, the CuZn related defects are decreased and consequently the band tailing and possible Fermi level pinning could be supressed. In addition, further adjusting [Zn]/[Sn] ratios in Zn-rich ACZTSe absorbers could be helpful to the performance of solar cells due to a fine modification of the carrier density and defects. After optimizing of chemical compositions by combining both modifications, the Ag alloyed Zn-rich ACZTSe based kesterite thin film solar cells have achieved the highest efficiency of 8.68%, in which the Ag alloying content with respected to [Ag]/([Ag]+[Cu]) and the [Zn]/[Sn] ratio are 10% and 1.14, respectively.

In this work, the alkali additive is introduced to improve the cycling stability of polyimide anode in saturated LiNO3 aqueous electrolyte. Optimal electrolyte consists of saturated LiNO3 aqueous solution with 0.001 mol L−1 KOH, which improves the capacity retention of polyimide in a three-electrode cell. When assembling with LiCoO2 cathode, the full cells exhibit good cycling stability with high capacity retention even after 1000 cycles. The remarkable improvement in cyclic performance is attributed to the efficient suppression of hydrogen ion accumulation in the electrolyte. Furthermore, theoretical calculation results indicate that the carbonyl interactions with hydrogen ions result in poor structural stability of the polymer. The formation of colloidal LiOH is realized/obtained by introducing an appropriate amount of KOH into the saturated LiNO3 electrolyte. The resulting colloidal LiOH not only reduces the concentration of free hydroxyl ions in the electrolyte, but also continuously releases the hydroxyl ions to react with hydrogen ions. These results suggest that the introduction of alkali in saturated LiNO3 aqueous electrolytes improves the electrochemical stability of polyimide anode, which will push the practical applications of polyimide materials in aqueous Li-ion cells.

Fabrication of carbon electrodes from noncarbonizable materials offers great potential to prepare high-performance supercapacitors at low cost. The present work reports a simple yet effective strategy for the preparation of hierarchical porous carbons using noncarbonizable polyvinylpyrrolidone (PVP) as a precursor. Thanks to the flame-retardant effect of phytic acid (PA), high carbonization yield of up to 40 wt% is obtained for the PVP-derived carbons. The subsequent activation endows the carbon material to have a hierarchical porous nanostructure with high surface area. The optimized aHPC-3-400 sample shows ultrahigh surface area (3090 m2 g−1) with moderate nitrogen (2.68 wt%) and abundant oxygen concentrations (23.47 wt%). The as-prepared electrode exhibits a high specific capacitance of 406 F g−1 at 1 A g−1 in 6 M KOH aqueous electrolytes. Remarkably, the assembled symmetric supercapacitor displays a high energy density of up to 28.9 W h kg−1 with a slight capacitance loss of 2% even after 10000 cycles. These results suggest that the flame retardant inspired stabilization strategy would provide a viable avenue for the preparation of high-quality carbon materials from noncarbonizable precursors.

Sb2S3 has attracted great research interest very recently as a promising absorber material for photoelectric and photovoltaic devices because of its unique optical and electrical properties and single, stable phase. However, the intrinsic high resistivity property of Sb2S3 material is one of the major factors restricting the further improvement of its application. In this work, the C60 modification of Sb2S3 thin films is investigated. The conductivity of Sb2S3 thin films increases from 4.71 × 10−9 S cm−1 for unmodified condition to 2.86 × 10−8 S cm−1 for modified thin films. Thin‐film solar cells in the configuration of glass/(SnO2:F) FTO/TiO2/Sb2S3(C60)/Spiro‐OMeTAD/Au are fabricated, and the conversion efficiency is increased from 1.10% to 1.74%.

Low-bandgap photovoltaic absorbers based on mixed tin-lead (Sn–Pb) halide perovskites offer promising opportunities to fabricate efficient multi-junction solar cells. However, the current Sn–Pb mixed perovskite solar cells (PSCs) were mainly prepared using lab-scale spin-coating, greatly hindering their application for large-area device fabrication. Here, we report a simple and robust methodology for scalable deposition of dense and uniform Sn–Pb mixed perovskite films by one-step blade coating. High quality perovskite films with different Sn–Pb ratios are readily prepared by vacuuming the freshly coated precursor films followed by an anneal process. Solar cells based on these bladed Sn–Pb mixed perovskite absorbers showed decent photovoltaic behaviors. Further enhancement of device performance was realized via surface defects passivation using phenethylammonium bromide (PEABr). It was found that the formation of a thin layer of 2D Ruddlesden-Popper perovskite on top of 3D bulk perovskite significantly suppressed charge recombination. As a consequence, the open-circuit voltage (VOC) of the solar cells (Eg = 1.35 eV) was dramatically lifted from 0.71 V to 0.78 V, yielding high efficiencies of over 15%. Moreover, notable improvement in shelf and moisture stability was observed due to the protection barrier of the 2D perovskite capping layer.

Al 2 O 3 :Cr 3+ nanocrystals have been developed as spectral converters for improving silicon cell photovoltaic conversion efficiency. In the Al 2 O 3 lattice, Cr 3+ ions act as broadband spectral acceptors by absorbing UV–vis (320–670 nm) photons, which are effectively converted into the strong red emission centered at around 696 nm, indicating Al 2 O 3 :Cr 3+ can be a good material for overcoming the so-called spectral mismatch in the silicon solar cell. The Al 2 O 3 :Cr 3+ nanocrystals are successfully introduced into tellurite glass to form transparent composites with good optical performance which can be characterized by photoluminescence (PL) spectra. These tellurite glass composites open a brand new field for the research of improving silicon solar cell photovoltaic conversion efficiency.