Search

Organic-inorganic hybrid perovskite solar cells (PSCs) have attracted great research attention due to their outstanding optoelectronic properties. The low-temperature synthesizing process of organic-inorganic hybrid perovskites can provide a significant advantage of reducing the manufacturing cost of solar cells. However, at the same time, this also brings challenges to PSCs in the form of long-term stability. Because of the low vacancy formation energy, organic-inorganic hybrid perovskites suffer from serious ion migration issue. Also, this ion migration will lead to a series of stability problems, which can hardly be addressed by encapsulation. Currently, modifying the surface of perovskite by an ion-blocking layer is a common strategy for achieving highly stable PSCs. These strategies could effectively address the stability issues caused by the interfacial ion diffusion between perovskite and the charge transport layer. However, the ion migration inside the perovskite layer could be still a knotty problem, which is difficult to be solved through surface modification. Herein, we propose a novel strategy to mitigate the internal ion migration by inserting two-dimensional graphene oxide (GO) into a perovskite layer. Close-space sublimation and ultrasonic spray coating were employed to prepare perovskite and GO layers, respectively. We found that the ion migration in the as-prepared perovskite/GO/perovskite can be successfully mitigated by the GO interlayer. As a result, the champion PSC with a GO interlayer maintained 85% of its initial power conversion efficiency (PCE) after 96 h of continuous illumination. By contrast, the efficiency of the PSC without a GO interlayer declined rapidly and maintained only 50% of the initial value. We believe that this novel interlayer strategy could provide a new idea and approach to preparing highly stable PSCs.

Achieving high-quality perovskite films with uniform morphology and homogeneous crystallinity is challenging owing to the coffee ring effect (CRE) in the spray-coating technologies. In this study, an evaporation/spray-coating two-step deposition method is used to fabricate Cs0.19FA0.81PbI2.5Br0.5 light harvesters for perovskite solar cells (PSCs). Considering the solid-liquid reaction, we establish a reaction-dependent regulating strategy that inhibits CRE successfully and prepare a high-quality perovskite layer, wherein the solvent for the FAI/Br solution during the spraying process is changed from isopropanol to n-butyl alcohol (NBA). The retarded-drying-enhanced spreading of the NBA solution inhibits contact line pinning to suppress the capillary flows and increases the reaction between metal halides (CsI/PbI2) and organic salts (FAI/Br), which result in a reduction in the accumulation of solutes in the periphery effectively inhibiting CRE. Consequently, we obtain a high performance Cs0.19FA0.81PbI2.5Br0.5 PSC with a power conversion efficiency (PCE) of 19.17%. An enlarged perovskite film (10 × 10 cm2) containing 40 sub-cells is prepared. The average PCE of these devices is 18.33 ± 0.56%, proving the reliability of the “coffee ring” regulating strategy. This study provides an effective approach for CRE controlment in spraying technology to achieve high repeatability devices with good performance.

Self-assembled glycine molecules are used to modify E-beam evaporated NiOx films. The glycine interlayer improved the crystallinity and band alignment of perovskite with NiOx. The all vacuum-processed PSCs achieved a champion PCE of 17.96% with negligible hysteresis.

To accelerate the commercial application of organic-inorganic hybrid perovskite solar cells (PSCs), it is necessary to develop simple and low-cost methods to prepare pinhole-free large-area perovskite films with high quality. A one-step blade coating method is regarded as a scalable technique. It is demonstrated that with the addition of N,N'-dimethylpropyleneurea (DMPU) in an FA-dominated perovskite precursor, a large-area high-quality perovskite film can be obtained by blade coating, achieving improved photovoltaic performance, thermal stability, and storage stability. It is found that the strong interaction between DMPU and Pb2+ ions is beneficial to delay the nucleation crystallization process, increase the size of crystal grains, and improve the crystallinity of the perovskite film. Planar n-i-p solar cells introducing DMPU exhibit power conversion efficiencies of 20.20% for 0.16 cm2 devices and 17.71% for 5 × 5 cm2 modules with an aperture area of 10 cm2. In addition, the devices without encapsulation placed at 50 °C for 500 h and with a relative humidity of 20 ± 5% for 1000 h still maintain efficiencies above 80 and 90%, respectively, showing outstanding stability.

The preparation of CsyFA1−yPbIxBr3−x-based perovskite by ultrasonic spraying has valuable application in the preparation of tandem solar cells on textured substrates due to its excellent stability and the advantages of large-area uniform preparation from the spraying technology. However, the bandgap of perovskite prepared by spraying method is difficult to adjust, and perovskites with a wide bandgap have the issue of phase instability. Here, we improved the crystallinity of the perovskite by simply controlling the post-annealing temperature. The results show that perovskite film prepared by hybrid spray method has the best crystallinity and device performance at a post-annealing temperature of 170 °C. On this basis, the bandgap of perovskite was changed from 1.53 eV to 1.76 eV by controlling the ratio of the organic halogen precursor solution. When the bandgap is 1.57 eV, a perovskite solar cell with an efficiency of 18.31% is obtained.

Formamidinium (FA)-based perovskite solar cells (PSC) show enhanced stability compared to their methylammonium (MA)-based counterparts. However, their stability needs to be further enhanced for the...

A novel aqueous Sn-S complex solution was applied as precursor to fabricate SnO2 electron selective layers (ESLs) for the hybrid perovskite solar cells (PSCs). The tin and sulfur powder were directly dissolved in a (NH4)2S water solution to form Sn-S precursor. After depositon and annealing, the SnO2 film was formed, presenting as a low cost and enviromental friendly method for preparation of ESL. The films showed excellent transmittance at visible wavelength range. Moreover, the method exhibited high compatibility for doping using Cu, Cd, Li, and Zn elements. Zn doping (0.05 M) in the as-prepared SnO2 ESL significantly improved perovskite solar cells (PSCs) performance. The highest PCE of 13.17% was achived with 15% enhancement compared to that of undoped SnO2 ESL samples. TiCl4 modifications on SnO2 film improved photovoltaic performance to 14.45%, but resulted in the poor long-term stability, around 80% more degredation than that of PSCs based on Zn-doped SnO2 films.

All-inorganic CsPbBr3 perovskite solar cells have triggered incredible interest owing to their superior stability, especially under high temperature conditions. Different from the organic–inorganic hybrid perovskites, inorganic CsPbBr3 perovskite always need a high annealing temperature for the formation of a cubic phase. Generally, the higher temperature (over 300 °C) and longer annealing time will promote the growth of CsPbBr3, resulting in larger grain sizes and lower trap density in the crystals. However, CsPbBr3 perovskite can also be damaged by excessive annealing temperature (∼350 °C) and time, since PbBr2 only has a melting temperature close to 357 °C. To address this issue, herein, we developed a novel pressure-assisted annealing method to prevent the sublimation of PbBr2 at high temperature. The CsPbBr3 films were firstly deposited by sequential thermal evaporation, and then annealed at 335 °C in an alloy pressure vessel. By controlling the pressure of the vessel, we obtained CsPbBr3 films with various morphologies. At normal atmospheric pressure, the as-prepared CsPbBr3 film exhibited small grain sizes and was full of pinholes. With the increase of annealing pressure, the grain sizes of the film showed a significant increasing trend, and the pinholes gradually vanished. When the pressure value came to 10 MPa, compact and uniform CsPbBr3 films with large grain sizes were obtained. Based on these films, CsPbBr3 perovskite solar cells with FTO/compact-TiO2/CsPbBr3/carbon architecture achieved a champion power conversion efficiency of 7.22%.

Preparing organic–inorganic hybrid perovskite films by deploying vacuum-based methods, which are widely used for industrial thin-film deposition, is expected to promote the commercialization of perovskite solar cells. In comparison with solution processes, vacuum-based deposition methods could provide some unique benefits for producing high-quality thin films, such as providing the ability to precisely determine the thickness of the film, producing a pinhole-free morphology, and high reproducibility. However, in the “two-step” method of preparing an organic–inorganic hybrid perovskite, the PbI2 films deposited using thermal evaporation are too dense to react with the organic component, leaving residual PbI2 in the perovskite. To address this issue, we developed a new doping strategy to help the crystal growth of Cs0.24FA0.76PbI3−xBrx perovskites in the vapor–solid reaction process. By introducing a moderate amount of SrI2 into the PbI2 layer, we successfully enhanced the reactivity of PbI2 and improved the crystallinity of these perovskites. As a result, the perovskite solar cell based on such Sr-doped Cs0.24FA0.76PbI3−xBrx films achieved a champion power conversion efficiency (PCE) of 17.66%. The device, without being encapsulated, maintained 95% of its initial PCE in an air atmosphere after 60 days. Moreover, the champion large-area (5 × 5 cm2) solar module exhibited a PCE of 13.92%, indicating the favorable uniformity of the Sr-doped Cs0.24FA0.76PbI3−xBrx film.

We developed a multiple sequential vacuum deposition method for the preparation of CsPbBr3 film with pure phase. Meanwhile, we found the annealing humidity plays an important role for the growth of CsPbBr3 crystal. By controlling the relative humidity at 30%, we obtained high-quality CsPbBr3 film with large grain size. As a result, a PCE of 8.86% has been achieved in the all-inorganic PSCs with a planar structure of FTO/compact TiO2/CsPbBr3/carbon.

In this research, we investigated the influence of phase transition in four standard perovskite materials on the device stability under thermal cycling (TC) condition, which is listed in International Electrotechnical Commission (IEC) stability tests criteria. The evolution of morphology, phase structure and charge carrier dynamics of four type perovskite materials throughout thermal cycling were analyzed. It was found that the cubic to tetragonal phase transition of MAPbI3 caused the quick degradation of the device, the α to δ phase transition in FAPbI3 and FA0.6MA0.4PbI3 resulted in sustained efficiency loss, while the FA0.9Cs0.1PbI3 was more stable compared to above three perovskites under the same test condition. The FA0.9Cs0.1PbI3 device retained nearly 88% of its initial efficiency after 200 temperature cycles between −30 °C and 85 °C, which could be ascribed to its successful stabilization of perovskite structure.

Although high efficiencies have been achieved for perovskite solar cells (PSCs), stability issues are still the key barriers for commercial applications. Herein, we carry out a systematic doping of non-radiative alkaline metal ions (Cs, Rb, K, Na, Li) to perovskite, studying their effects on perovskite morphology, electrical stability and performance of PSCs. The hysteresis related stability issues are also investigated at different conditions, such as steady-state power output, aging, repeated voltage sweeping, varied pre-scan voltage bias, etc. It is found the hysteresis becomes much severer at different test conditions for the devices doped with small sized Li and Na. While the subsized Rb and K ions (compared to Cs) doping can significantly enhance the crystallinity of perovskite and reduce the hysteresis that is also more stable. The crystallization, morphologies, time-resolved photoluminescence, electrochemical impedance spectroscopy were conducted to investigate the properties of the doped perovskite films to understand the relationship between the film quality and device performance. With a proper combination of Cs, Rb, K ions doping in PSCs, a high PCE over 20% is achieved with an enhanced electrical stability. Moreover, an over 17% efficiency 7 × 7 cm2 perovskite solar cell module is realized by this strategy, with a certified PCE of 16.5% (aperture area of 20.78 cm2) without hysteresis.

Tin oxide (SnO2) is widely used as electron transport layer (ETL) material in perovskite solar cells (PSCs). Numerous synthesis methods for SnO2 have been reported, but they all require a proper thermal treatment for the SnO2 ETLs. Herein we present a simple method to synthesize SnO2 nanoparticles (NPs) at room temperature. By using butyl acetate as a precipitator and a proper UV–Ozone treatment to remove Cl residuals, excellent SnO2 ETLs were obtained without any thermal annealing. The highest power conversion efficiency (PCE) of the prepared PSCs was 19.22% for reverse scan (RS) and 18.79% for forward scan (FS). Furthermore, flexible PSCs were fabricated with high PCEs of 15.27%/14.74% (RS/FS). The low energy consuming SnO2 ETLs therefore show great promise for the flexible PSCs' commercialization.

Despite the impressive photovoltaic performance with a power conversion efficiency beyond 23%, perovskite solar cells (PSCs) suffer from poor long-term stability, failing by far the market requirements. Although many efforts have been made towards improving the stability of PSCs, the thermal stability of PSCs with CH3NH3PbI3 as a perovskite and organic hole-transport material (HTM) remains a challenge. In this study, we employed the thermally stable (NH2)2CHPbI3 (FAPbI3) as the light absorber for the carbon-based and HTM-free PSCs, which can be fabricated by screen printing. By introducing a certain amount of CsBr (10%) into PbI2, we obtained a phase-stable CsxFA1−xPbBrxI3−x perovskite by a “two-step” method and improved the device power conversion efficiency from 10.81% to 14.14%. Moreover, the as-prepared PSCs with mixed-cation perovskite showed an excellent long-term stability under constant heat (85 °C) and thermal cycling (−30 °C to 85 °C) conditions. These thermally stable and fully-printable PSCs would be of great significance for the development of low-cost photovoltaics.

The preparation of Cs

Photovoltaic technology offers a sustainable solution to the problem of soaring global energy demands. Recently, metal halide perovskite solar cells (PSCs) have attracted worldwide interest because of their high power conversion efficiency of 25.5% and great potential in becoming a disruptive technology in the photovoltaic industry. The transition from research to commercialization requires advancements of scalable deposition methods for both perovskite and charge transporting thin films. Herein, we share our view regarding the current challenges to fabrication of PSCs by printing techniques. We focus particularly on ink technologies, and summarize the strategies for printing uniform, pinhole-free perovskite films with good crystallinity. Moreover, the stability of perovskite solar modules is discussed and analyzed. We believe this review will be advantageous in the area of printable electronic devices., This review details recent progress on perovskite solar cells fabricated by printing processes, and highlights how ink engineering realizes stable perovskite solar modules with high efficiency.

In this study, high quality Cs

Perovskite solar cells (PSCs) have rapidly developed and achieved power conversion efficiencies of over 20% with diverse technical routes. Particularly, planar-structured PSCs can be fabricated with low-temperature (≤150 °C) solution-based processes, which is energy efficient and compatible with flexible substrates. Here, the efficiency and stability of planar PSCs are enhanced by improving the interface contact between the SnO

All-inorganic CsPbBr

Perovskite solar cells (PSCs) have reached an impressive efficiency over 23%. One of its promising characteristics is the low-cost solution printability, especially for flexible solar cells. However, printing large area uniform electron transport layers on rough and soft plastic substrates without hysteresis is still a great challenge. Herein, we demonstrate slot-die printed high quality tin oxide films for high efficiency flexible PSCs. The inherent hysteresis induced by the tin oxide layer is suppressed using a universal potassium interfacial passivation strategy regardless of fabricating methods. Results show that the potassium cations, not the anions, facilitate the growth of perovskite grains, passivate the interface, and contribute to the enhanced efficiency and stability. The small size flexible PSCs achieve a high efficiency of 17.18% and large size (5 × 6 cm2) flexible modules obtain an efficiency over 15%. This passivation strategy has shown great promise for pursuing high performance large area flexible PSCs., Uniformity and hysteresis are long lasting problems for flexible perovskite solar modules. Here Bu et al. develop a universal potassium passivation strategy to improve the quality of slot-die printed tin oxide electron transport layers and demonstrate highly efficient and hysteresis-free flexible devices.

Low-temperature solution-processed SnO2 as a promising electron-transport material for planar perovskite solar cells (PSCs) has attracted particular attention because of its outstanding properties such as high optical transparency or high electron mobility. However, low-temperature sol-gel processes used in the synthesis are inevitably affected by the humidity of the atmosphere, which results in a wide distribution in the performance of the prepared PSCs owing to the inability to control crystallinity and defects. Herein, a highly crystalline SnO2 film is synthesized using a simple water bath post-treatment, which can remove the surface residuals of SnCl4 on the SnO2 films, which is beneficial for the interface charge transport from the perovskite to the SnO2 electron-transport layer. An improved performance of the PSCs can be easily obtained applying this treatment, giving rise to a high power conversion efficiency (PCE) of 19.17 %, much higher than that of the pristine SnO2 -based device (17.59 %). Most importantly, the reproducibility of the devices has been greatly improved, independent of the environmental humidity. Therefore, the enhanced crystallinity of SnO2 has shown promise for future commercial PSC applications: 5 cm×5 cm PSC modules have achieved a PCE of 16.16 %.

Making perovskite solar cell technology commercially viable is facing a challenge that scaling-up of a small device always experiences a substantial reduction in power conversion efficiency (PCE). In this research, we adopted a volume expansion routine to scale-up from a 0.16 cm2 laboratory-scale device to large size perovskite solar module (PSM) with a PCE loss of 8% and reached a certified PCE of 13.98%. The PCE of the PSM with Au electrode dropped about 40% of the initial efficiency after 16 days’ storage, while the efficiency of PSM with Cu as counter electrode retained 90% of the initial after 30 days’ storage. We also introduced hot spots heating (HSH) characterization method to investigate the stability of PSM. HSH reveals that Cu electrode greatly reduces numbers of hot spots and extent of temperature increase in a PSM compared with Au electrode. Therefore, counter electrode also plays an important role in the stability improvement of PSM.

Summary High-performance perovskite solar cells require efficient extraction of photogenerated electrons from the light absorber to the semiconductor skeleton, which can simultaneously stabilize the photovoltaic device by kinetically suppressing superoxide-intermediated degradation by reducing the accumulation of electrons in the perovskite layer. Here, we propose to improve and stabilize the photovoltaic performance of the cells by modulating the surface structures of TiO 2 . The transformed rutilized phase not only bridges the perovskite-TiO 2 interfacial charge transfer but also protects the light absorber from ultraviolet-induced degradation by suppressing the survival of holes generated in the TiO 2 skeleton. As a result of these merits, an increment of 50% in power conversion efficiency can be achieved. Furthermore, these cells exhibit extraordinary stability under continuous (120 hr) power-maximum output without cell encapsulation in the presence of moisture, oxygen, and ultraviolet irradiation and can restore to their initial photovoltaic performance by repeatedly undergoing tetragonal-to-cubic phase transition of the perovskite.

Perovskite solar cell (PSC) has drawn widespread concern for its high efficiency and facile low-temperature solution fabrication, promising for the alternative low-cost photovoltaic energy. However, before commercializing, the problems regarding to the environmental stability and electrical hysteresis of PSCs still need to be tackled. We present a simple route by stacking n-type materials TiO2 (spray pyrolysis) and SnO2 (aqueous colloidal) for planar devices, and achieve a stable (~91% efficiency >90 days at 30%RH without encapsulation), hysteresis-free (hysteresis index 0.004) and efficient (18.03%) perovskite solar cells. Moreover, we carry out a system stability evaluation for unsealed devices under harsh conditions with intense UV illumination, heat and damp in an environmental chamber. Both TiO2 and SnO2 devices demonstrate inferior performance compare to the stacked samples in the accelerated stability tests. Photoluminescence, phase and electrical characterizations suggest that the performance enhancement is ascribed to the synergetic optimization from concealing the defective interface and promotion of carriers transfer and blocking. With the optimized n-type layers, a high efficiency of 14.39% is obtained for the 5 × 5 cm2 sub-module. These results suggest that by stacking n-type layers could enable superior overall performances to common electron transport layers (ETLs) (TiO2, SnO2 and etc.), providing facile routes for fabricating efficient PSCs with high stability.

Large-area, highly uniform CsxFA1−xPbI3−yBry mixed cation perovskite films were prepared by a facile vapor–solid reaction method. In this method, CsBr and PbI2 were first deposited via thermal evaporation, and then exposed to FAI/FACl vapor to form the CsxFA1−xPbI3−yBry perovskite. With the incorporation of CsBr, the crystallinity of the FAPbI3 perovskite could be significantly improved. Meanwhile, the FACl vapor could accelerate the growth rate of the CsxFA1−xPbI3−yBry perovskite in the vapor–solid reaction process. By optimizing the content of Cs and the ratio of FACl/FAI, we obtained high quality, pin-hole free Cs0.24FA0.76PbI3−yBry films. Based on these films, the small sized perovskite solar cells (PSCs) reached a champion power conversion efficiency (PCE) of 17.29%. Without encapsulation, the device with the Cs0.24FA0.76PbI3−yBry perovskite showed much better moisture and thermal stability in comparison to that with the pristine FAPbI3 perovskite. Furthermore, we also fabricated PSC modules with a size of 8 × 8 cm2 and achieved a PCE of 12.24%, indicating that such a vapor–solid reaction method has a certain superiority in the manufacture of large-scale PSCs.

Organic and inorganic molecules/atoms located at different lattice positions in hybrid perovskite films play various roles in crystallization and carrier transport for perovskite films. For efficient and stable solar devices, high quality crystals and the proper dispersion of organic/inorganic species are required. In a preferably mixed perovskite system (a blend of MA, FA, I, Br, etc.), however, the effects of inorganic/organic ratios on the performances and electrical properties of perovskite solar cells have not been fully understood. Here, we present perovskite solar cells with self-doped organic and inorganic components to investigate in detail their effect on crystallization and electrical properties. The organic component enhances the conductivity and reduces the hysteresis, while the inorganic component promotes crystal growth. A critical composition is beneficial to perovskite crystallization, with larger crystals and a pinhole-free morphology, and the corresponding device achieved a high efficiency over 19.14% (0.16 cm2, mask area) and 16.2% at an area of 1.21 cm2. Thus, evaluation of the organic/inorganic variation effects provides an understanding of self-doping in mixed perovskites and is beneficial to pursue high-performance perovskite devices.

Cs/FA(CH(NH2)2+)/MA(CH3NH3+) triple cation composition engineering is considered as an effective strategy to achieve high performance devices due to the excellent bandgap, uniform film and highly thermal stability. However, hysteresis, as a common phenomenon in perovskite solar cells (PSCs), of the triple-cation perovskite based PSCs has become a complex issue to be solved on the road to the commercialization of PSCs. The introduction of Cs into small perovskite grains resulted in more grain boundaries for ions accumulation. Herein, we demonstrate a unique method to suppress J–V hysteresis and enhance the photoelectric performance via Cl doping into a CsFAMA precursor. We found that the grain size, perovskite crystallinity, and charge carrier lifetime significantly improved with the Cl incorporation. By optimizing the molar ratio of MABr and PbCl2, we achieved the optimal Cl-doped concentration in the perovskite film. 19.14% efficiency for a small area cell and 15.11% efficiency for a 5 × 5 cm2 large area mini-module were achieved based on the mesoporous structured devices. These results suggest that Cl-incorporated triple-cation perovskite (labeled CsFAMAClx) is an attractive absorber for producing efficient large area PSCs.

Inorganic–organic hybrid perovskite solar cells (PSCs) have drawn great attention in the past several years. As the stability of PSCs has been a major obstacle for their commercialization, a lot of work has been focused on improving the long-term stability. Here, we reported a meso-structured mixed PSC employing poly(3-hexylthiophene-2,5-diyl) (P3HT) as a hole transport layer (HTL) showing a stable performance even after one year of exposure to air. The impact of different HTL thicknesses on the power conversion efficiency (PCE) of the PSCs has been investigated. The performance of the PSCs was further improved by doping Li-salt/4-tert-butylpyridine into the P3HT HTL. A maximum PCE of 17.55% was achieved, superior to the 14.30% PCE of the pristine P3HT-based devices. The effect of the dopants on the stability of the devices has also been studied.

Compared with traditional rigid perovskite solar cells fabricated on glass, flexible perovskite solar cells have a wider range of applications due to their lightweight and bendability, which have attracted great attention. Besides, carbon materials have shown some advantages of abundance, long-term stability and appropriate energy level as top electrode in perovskite solar cells. However, the reports of flexible devices based on carbon electrode are quite rare for the mismatch between the configuration of flexible perovskite solar cells and common carbon electrode techniques. Here, we introduce carbon film electrode into flexible perovskite solar cells for the first time. A new composite carbon film electrode is prepared on a highly conductive and flexible substrate of conductive cloth. Considerable PCEs of 15.37% and 14.05% have been obtained in small area (0.1 cm2) and large area (1 cm2) carbon based flexible devices, respectively. The comparable performance with standard Au electrode device, enhanced stability and suitability for roll-to-roll manufacturing reveals promising application of this low-cost composite carbon electrode.

Organic–inorganic metal halide perovskite solar cells (PSCs) have made a striking breakthrough with a power conversion efficiency (PCE) over 22%. However, before moving to commercialization, the hysteresis of PSCs, characterized as an inconsistent photovoltaic conversion property at varied electric fields, should be eliminated for stable performance. Herein, we present a novel quadruple-cation perovskite absorber, KxCs0.05(FA0.85MA0.15)0.95Pb(I0.85Br0.15)3 (labeled as KCsFAMA), with which the hysteresis in PSCs can be fully eliminated irrespective of the electron transportation layers. The incorporation of potassium intensively promotes the crystallization of the perovskite film with a grain size up to ∼1 μm, doubled compared to the K free counterparts. Further characterization revealed that a lower interface defect density, longer carrier lifetime and fast charge transportation have all made contributions to the hysteresis-free, stable and high PCE (20.56%) of the KCsFAMA devices. Moreover, we present a 6 × 6 cm2 sub-module with the KCsFAMA composition achieving a high efficiency of 15.76% without hysteresis. This result suggests that the quadruple-cation perovskite is a highly attractive candidate for future developments of efficient and stable PSC modules.

This work draws attention to environmental influence to function layers interfaces and the band alignment optimization of organic-inorganic metal halide planar perovskite solar cell (PSC), demonstrating an effective route to enhance the PSC photovoltaic conversion efficiency (PCE) and stability. The PCE of the PSC presents a sensitive correlation with the relative humidity (RH) during the electron transport layer (ETL) preparation. Through optimizing the RH condition, the PSCs show outstanding performances using sol-gel TiO 2 ETL prepared under 55 RH%. Moreover, we systematically investigate the Zr doping effect in the TiO 2 ink with a variation of Zr molar percentages from 0% to 7.5%. A high PCE of 15.06% with a good fill factor of 0.76 is obtained at 2 mol% Zr doping, in contrast to 12.25% of the undoped device. The Mott-Schottky analysis reveals that the elevated open-circuit voltage ( Voc ) is attributed to the upshifting of flat band potential of TiO 2 from −4.15 eV to −4.02 eV (vs. vacuum) after doping. Notably, the as-made cell shows low hysteresis and elevated stability with only 15% degradation of PCE (35% for PSC with pyrolyzed TiO 2 ) after 550 h/14 RH% ageing without encapsulation.

Solution-processed organic-inorganic lead halide perovskites have shown photovoltaic performance above 23 %, attracting great attention. However, the champion devices require fabrication in a controlled inert/dry atmosphere. The development of highly efficient and stable perovskite solar cells under high-humidity atmosphere conditions for future commercialization is still challenging, especially for CH3 NH3 PbI3 (MAPbI3 ), which is vulnerable to moisture. In this study, a large-sized tert-butylammonium [C(CH3 )3 NH3 + ] organic cation was incorporated into the MAPbI3 crystalline structure, which could form a more stable 3 D crystalline structure and alleviate the decomposition caused by the humidity. It delivered a power conversion efficiency of 19.3 % upon preparation under a humid environment condition of 50 % relative humidity as well as improved humidity and thermal stability. Our work provides a facile strategy for improving perovskite performance and stability by introducing a new chemical additive for the future application of perovskite solar cells.

Despite the impressive photovoltaic performance with a power conversion efficiency beyond 23%, perovskite solar cells (PSCs) suffer from poor long-term stability, failing by far the market requirements. Although many efforts have been made towards improving the stability of PSCs, the thermal stability of PSCs with CH

Tin oxide (SnO

We design and construct a new type of solid-state electrochromic batteries powered by perovskite solar cells for smart windows. In addition to optical modulation, this integrated system can exhibit multifunctionality of solar energy harvesting, electrochemical energy storage and reutilization. The solid-state electrochromic batteries are composed of a reduced graphene (rGO)-connected bilayer NiO nanoflake array cathode and a WO3 nanowire array anode. The charge storage and release are accompanied by color changes (between transparent and blue) and relatively fast (2.5–2.6 s) and large optical modulation (up to 62% at the infrared range, 1000–2000 nm). The electrochromic batteries can act as a power source and exhibit a capacity of 75 mA h g−1 at 1 A g−1 and good cycling life.