Search

We fabricate polymer solar cells (PSCs) and modules by sheet‐to‐sheet slot‐die coating under air environment based on halogen‐free host solvent. How to upscale small‐area PSC to large‐area PSC module is demonstrated here. The opaque module exhibits the most superior performance among the slot‐die‐coated modules reported. The scaling of both the semitransparent top electrode and PSC module is a challenge due to the complex difficulties. In this study, the semitransparent MoO3/Ag/MoO3 top electrode is successfully upscaled to be in the large‐area semitransparent PSC module. Ag layer thickness as reflector in the tri‐layer electrode is used to tune the trade‐off between transmittance, conductivity, and the light absorption in the active layer. The matching combination of transmittance, absorption spectra of MoO3/Ag/MoO3 top electrode, and active layer is a main key of our approach greatly improving photovoltaic and optical performance. The power conversion efficiencies (PCEs) of the semitransparent PSC modules with Ag thickness of 25, 20, and 15 nm are 7.1%, 5.9%, and 4.4%, respectively. The corresponding average visible transmittance (AVT) values are 20.5%, 28.3%, and 36.1%, respectively. The transmittance values at 550 nm are ranging from 24% to 40%. According to the review of all the reported semitransparent modules (>10 cm2), our modules demonstrate the excellent trade‐off performance about two times better than the large‐area semitransparent PSC modules currently reported either based on the similar PCEs or AVTs. [ABSTRACT FROM AUTHOR]

• Halogen-free and ambient slot-die coating of the small-molecule organic solar cell and module. • Thermal annealing for mass production, good photo-stability and indoor lighting performance. • Tunable BHJ film morphologies of sheet-to-sheet and flexible roll-to-roll slot-die coatings. • Efficiency of S2S and flexible R2R slot-died SMOSC achieve 7.6% and 7.3%, respectively, • Characteristic, structural and systematic study correlating processing and performance. The upscale fabrication of the inverted small-molecule organic solar cell (SMOSC) from spin coating to large-area slot-die coating using halogen-free solvent under the ambient air environment is developed. This work successfully adopts thermal annealing treatment to tune the bulk heterojunction (BHJ) structure for two advantages of compatibility to mass production and good photo-stability. By tuning the respective optimum film structure, the power conversion efficiency (PCE) values under AM 1.5G light and indoor light (T5 lamp with 500 lx) illuminations for the ambient spin-coated device achieve 8.5% and 13.26%, respectively. The photo-bleaching and light-soaking tests under the AM 1.5G illumination show that the photo-stability of the thermally-annealed DRCN5T:PC 71 BM device is much better than PTB7-Th:PC 71 BM device. The tunable BHJ film morphologies of large-area ITO/glass-based sheet-to-sheet (S2S) and flexible roll-to-roll (R2R) slot-die coatings of DRCN5T:PC 71 BM SMOSCs are based on different dry-film formation and crystallization mechanisms. The structural control during the drying-film process for S2S and R2R coatings is a critical key to determine the optimum performance. The PCEs of the ITO/glass-based and flexible ITO/PET-based SMOSCs achieve 7.6% and 7.3%, respectively. The PCE of the ambient flexible R2R slot-die-coated SMOSC using halogen-free solvent is much higher than that of the currently flexible R2R coated SMOSCs. The PCEs of S2S slot-die-coated cell device of 1 × 5 cm2 and module achieve 5.1%. We conduct a characteristic, structural and systematic study of how to scale-up SMOSC via slot-die coatings, demonstrating the relationship among processing control, performance and structure for different coatings. [ABSTRACT FROM AUTHOR]

Abstract: For the first time, the plasmonic gold bipyramids (Au BPs) are introduced to the PbS colloidal quantum dot (CQD) solar cells for improved infrared light harvesting. The localized surface plasmon resonance peaks of Au BPs matches perfectly with the absorption peaks of conventional PbS CQDs. Owing to the geometrical novelty of Au BPs, they exhibit significantly stronger far‐field scattering effect and near‐field enhancement than conventional plasmonic Au nanospheres (NSs). Consequently, device open‐circuit voltage (Voc) and short‐circuit current (Jsc) are simultaneously enhanced, while plasmonic photovoltaic devices based on Au NSs only achieve improved Jsc. The different effects and working mechanisms of these two Au nanoparticles are systematically investigated. Moreover, to realize effective broadband light harvesting, Au BPs and Au NSs are used together to simultaneously enhance the device optical and electrical properties. As a result, a significantly increased power conversion efficiency (PCE) of 9.58% is obtained compared to the PCE of 8.09% for the control devices due to the synergistic effect of the two plasmonic Au nanoparticles. Thus, this work reveals the intriguing plasmonic effect of Au BPs in CQD solar cells and may provide insight into the future plasmonic enhancement for solution‐processed new‐generation solar cells. [ABSTRACT FROM AUTHOR]

This study reports the fabrication of stable, high-performance, simple structured tandem solar cells based on PbS colloidal quantum dots (CQDs) under ambient air. This study also reveals detailed device engineering to deposit each functional layer in the subcells at low temperature to avoid damage to the PbS CQDs and meanwhile makes the fabrication process compatible to flexible plastic substrate. Two efficient recombination layers (RLs) are rationally designed to connect the two subcells in series. The use of solution-processed RL with an organic PEDOT:PSS (poly(3,4-ethylenedioxythiophene): polystyrene sulfonate) interlayer leads to the fabrication of the tandem devices in solution process. The use of robust inorganic RL containing an ultrathin Au interlayer results in more efficient device performance and remarkably improved device lifetime. The optimal PbS CQDs tandem cells based on inorganic RL demonstrate a high power conversion efficiency approaching 9%. This efficiency is more than two times higher than the previous record of 4.2%, which has been kept for more than five years. The remarkable stability, high performance, and low-temperature processing of these tandem devices may provide insight into the commercialization of flexible and large-area CQDs tandem solar cells in the near future. [ABSTRACT FROM AUTHOR]

We have developed an improved small-angle X-ray scattering (SAXS) model and analysis methodology to quantitatively evaluate the nanostructures of a blend system. This method has been applied to resolve the various structures of self-organized poly(3-hexylthiophene) /C61-butyric acid methyl ester (P31-IT/PCBM) thin active layer in a solar cell from the studies of both grazing-incidence small-angle X-ray scattering (GISAXS) and grazing-incidence X-ray diffraction (GIXRID). Tuning the various length scales of PCBM-related structures by a different annealing process can provide a flexible approach and better understanding to enhance the power conversion of the P3HT/PCBM solar cell. The quantitative structural characterization by this method includes (1) the mean size, volume fraction, and size distribution of aggregated PCBM clusters, (2) the specific interface area between PCBM and P3HT, (3) the local cluster agglomeration, and (4) the correlation length of the PCBM molecular network within the P3HT phase. The above terms are correlated well with the device performance. The various structural evolutions and transformations (growth and dissolution) between PCBM and P3HT with the variation of annealing history are demonstrated here. This work established a useful SAXS approach to present insight into the modeling of the morphology of P3HT/PCBM film. In situ GISAXS measurements were also conducted to provide informative details of thermal behavior and temporal evolution of PCBM-related structures during phase separation. The results of this investigation significantly extend the current knowledge of the relationship of bulk heterojunction morphology to device performance. [ABSTRACT FROM AUTHOR]

Vacuum Fabrication: Efficient Cesium Lead Halide Perovskite Solar Cells through Alternative Thousand-Layer Rapid Deposition (Adv. Funct. Keywords: alternative deposition; cesium; perovskite solar cells; vacuum deposition Alternative deposition, cesium, perovskite solar cells, vacuum deposition. [Extracted from the article]

The novel growth of cesium lead halide perovskite thin films, which are prepared through thousand‐layer rapid alternative deposition, is performed by developing an active perovskite film consisting of a layer‐by‐layer structure. This method is considerably more difficult to be implemented from the solution process. The obtained thin film morphology and characteristics are distinguished from that of the traditional a few layers and two‐material codeposition. These alternative deposited perovskites are integrated with vacuum‐deposited carrier‐transporting layers and electrodes, and all vacuum‐sublimed perovskite solar cells exhibit an outstanding power conversion efficiency of 13.0%. The use of these devices for environmental light energy harvesting provides a power conversion efficiency of 33.9% under fluorescent light illumination of 1000 lux. [ABSTRACT FROM AUTHOR]

The structural characterization correlated to the processing control of hierarchical structure of planar heterojunction perovskite layer is still incomplete due to the limitations of conventional microscopy and X-ray diffraction. This present study performed the simultaneously grazing-incidence small-angle scattering and wide-angle scattering (GISAXS/GIWAXS) techniques to quantitatively probe the hierarchical structure of the planar heterojunction perovskite solar cells. The result is complementary to the currently microscopic study. Correlation between the crystallization behavior, crystal orientation, nano- and meso-scale internal structure and surface morphology of perovskite film as functions of various processing control parameters is reported for the first time. The structural transition from the fractal pore network to the surface fractal can be tuned by the chloride percentage. The GISAXS/GIWAXS measurement provides the comprehensive understanding of concurrent evolution of the film morphology and crystallization correlated to the high performance. The result can provide the insight into formation mechanism and rational synthesis design. [ABSTRACT FROM AUTHOR]

• A fast AM1.5G light treatment is introduced to permanently reduce trap-assisted recombination in polymer solar cell. • The 10-second AM1.5G light exposure can enhance the efficiency of flexible polymer solar modules from 10.08% to 14.5%. • The treated flexible polymer solar modules show high stability under dark, TL84 light exposure, and office condition. • The enhanced flexible polymer solar module integrated with power management can power a temperature sensor over 485 days. In recent years, the rapid advancement of the Internet of Things (IoT) has driven the demand for innovative and eco-friendly powering solutions to reduce pollution from conventional batteries. Polymer Solar Cells (PSCs) have emerged as a promising candidate, especially for harvesting energy from indoor artificial light sources. This study introduces a novel method to significantly enhance the indoor performance of all solution slot-die coated PSCs, including both devices and modules, by addressing a key issue: trap-assisted recombination. Through a brief 10-second AM1.5G light treatment applied to the PSCs, we have been able to permanently mitigate the trap-assisted recombination phenomena. Devices using either MoO 3 or HTL3 as hole transport layers have demonstrated enhanced indoor performance after the treatment, which can be attributed to reduced traps and improved conductivity. Moreover, the encapsulated flexible modules with HTL3 have exhibited good stability in varied conditions, including dark storage, continuous TL84 indoor light illumination, and a typical office condition. When integrated with a temperature sensor and power management system, both the PV2001:PC 71 BM and PV-X (as the active layer) based HTL3-modules can operate uninterruptedly for durations exceeding 370 and 485 days, respectively. This finding emphasizes the potential of PSCs in powering IoT components in upcoming years. [ABSTRACT FROM AUTHOR]

Graphical abstract Feasible commercial process to manufacture highly efficient perovskite solar cells. Highlights • A rapid and nitrogen-free process for the fabrication of planar inverted structured perovskite solar cells (PSCs). • An alternative post-annealed method was developed by near-infrared (NIR) radiation to traditional heating oven. The annealed time can be shorten from 1500 s to 30 s by NIR irradiation. • The crystalline and nano-morphological structures of perovskite layers correlated to thermal and NIR annealing effects were revealed by the grazing-incidence wide-angle and small-angle X-ray scattering (GIWAXS and GISAXS). • Performance of sheet-to-sheet slot-die coated PSCs fabricated under ambient air can be achieved to 12.3%. Abstract A nitrogen-free and slot-die coating fabrication of perovskite solar cells combined with NIR annealing. We develop a fabrication approach of planar inverted structured perovskite solar cell (PSC) in ambient condition with a PCE of 12.4% as compared to that (13.3%) of PSC fabricated in glove box filled with nitrogen. In addition, we demonstrate an alternative post-annealed method by near-infrared (NIR) radiation to traditional heating method by oven. The annealed time by NIR can be shortened from 1500 s to 30 s and the device performance over 10% can be achieved. The present work investigates the NIR effect for different layers in the two-step processing on the cell performance. The grazing-incidence wide-angle and small-angle X-ray scattering (GIWAXS and GISAXS) techniques for the perovskite layers are performed to reveal the crystalline and nano-morphological structures of perovskite layers correlated to thermal and NIR annealing effects. Based on this approach under ambient air, we scale up to the large-area fabrication using the slot-die coating. The performance of slot-die coated PSC can achieve to 12.3%. The critical step is the control of PbI 2 layer thickness. We also applied the NIR radiation to the slot-die coated PSC and the PCE of 11.4% can be achieved. Our study paves a facile way to rapid manufacture and mass production of perovskite solar cells. [ABSTRACT FROM AUTHOR]

In this article, the effect of hole transport layer (HTL) on the thermal stability of inverted polymer solar cells (PSCs) consisting of the blend of poly(3-hexylthiophene) (P3HT) and (6,6)-phenyl-C 60 butyric acid methyl ester fullerene derivative (PCBM) as active layer (AL) is investigated. The two conventional HTLs, poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) and MoO 3 , were used in this study to demonstrate the effect of HTLs on the thermal stability of PSCs. The inverted devices were heated at 80–110 °C as accelerated test for different time intervals to illustrate the temporal variation of performance. The different temporal behaviors during (1) metastable period and (2) thermally unstable period are described here. Moreover, the effect of photoactive film thickness on the thermal stability of devices based on the two HTLs was considered. This study shows that the spin- and spray-coated devices exhibit different characteristics of thermal stability for the PSCs with MoO 3 and PEDOT:PSS as HTLs, respectively. The temporal behavior caused by the effect of HTL during the thermally-unstable period is quantitatively studied. This study could provide vital information required to develop high durability in commercial PSCs. [ABSTRACT FROM AUTHOR]

We systematically investigated the thermal effects of drying process as well as thermal annealing on morphology and performance of inverted polymer solar cells (PSCs) fabricated by roll-to-roll (R2R) slot-die coating. Power conversion efficiency (PCE) of PSCs layer is strongly influenced by bulk heterojunction (BHJ) active layer. Compared to the conventional annealing process, we demonstrate that the drying process for transforming the wet active layer into solid-state film (an early polymer crystallization step) in the R2R process is a critical control of morphological evolution to the desired structure. We have demonstrated that a significant improvement in performance of inverted PSCs can be achieved by tuning the parameters in the drying process prior to the annealing process. This study provides the mechanistic understanding of how the drying and annealing processes affect the morphological evolution regarding to the crystallinity, BHJ structure and interface between layers. Moreover, with respect to environmental concerns, halogen-free are carried out as an alternative solvent to halogenated solvents. We successfully incorporate halogen-free solvent, o-xylene, with an elevated drying temperature for improving the performance of R2R slot-die coated inverted solar cells. [ABSTRACT FROM AUTHOR]

For attaining the commercialization, the large-area roll-to-roll (R2R) slot-die-coated inverted polymer solar cells (PSCs) would be promising. The electron transport layer (ETL) plays an important role in scale-up development from small PSCs. In this work, the active layer comprising poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C 61 -butyric acid methyl ester (PCBM) and sol–gel zinc oxide (ZnO) ETL were slot-die coated on flexible PET/ITO substrate as reference based on the R2R process. Aluminum-doped ZnO (AZO) instead of ZnO was also adopted. For further improving the performance of large-area PSC, we used polyethylenimine ethoxylated (PEIE) material to tailor the nanostructure of ZnO and AZO ETLs for reducing the surface traps on ETLs using two approaches: (1) ZnO/PEIE bilayer formed by sequential deposition and (2) ZnO:PEIE hybrid composite as ETLs. The present work would demonstrate the optimum material (fabrication) parameters and how the performance of the R2R large-area slot-die coated PSC can be improved by modifying the ZnO- and AZO-based ETL structures. We also perform the various measurements and structural characterization to understand the relationship among R2R slot-die coating process, charge transport properties, film structure and photovoltaic performance as increasing the device areas from 1×0.3 cm 2 (power conversion efficiency: 2.69%) to 1×1 cm 2 . [ABSTRACT FROM AUTHOR]

Highlights: [•] ITO-free PSCs fabricated by a combination of inkjet-printing and spray processes. [•] Ink-jet printed Ag grids covered with highly conductive PEDOT:PSS was used as anode. [•] Improved interfacial contact between Ag grids and active layer resulted in high PCE. [•] Improving performance of large-area (8cm2) PSCs is shown. [Copyright &y& Elsevier]

Abstract: In this paper, the use of hot solvent vapor (HSV) annealing is demonstrated to improve the performance of polymer solar cells (PSCs) fabricated by the spray process. The blend of poly(3-hexylthiophene) and [6,6]-phenyl-C61-butyric acid methyl ester (P3HT/PCBM) is used as a photoactive layer of the solar cell. Compared to the conventional solvent vapor annealing, the HSV annealing can eliminate the formation of intra-droplet boundary during the spray process and optimize the nanostructure of the film quickly (≤5min). The study of conducting atomic force microscopy (C-AFM) reveals that the HSV annealed film exhibits smooth film surface and homogenous conductivity distribution. Moreover, an enhanced light harvesting and increased crystallinity of P3HT in the active layer are observed by UV–vis absorption and X-ray diffraction (XRD). With subsequent thermal annealing, the power conversion efficiency of solar cell made from the HSV annealed film is reached at 3.61%. This HSV annealing technique can be implemented into the fabrication of high efficient large-area PSCs using the spray process. [Copyright &y& Elsevier]