Fully printed perovskite solar cells are demonstrated with slot‐die coating, a scalable printing method. A sequential slot‐die coating process is developed to produce efficient perovskite solar cells ...and to be used in a large‐scale roll‐to‐roll printing process. All layers excluding the electrodes are printed and devices demonstrate up to 11.96% power conversion efficiency. It is also demonstrated that the new process can be used in roll‐to‐roll production.
Organic–inorganic halide perovskite solar cells (PeSCs) have attracted worldwide attention due to their excellent photovoltaic properties, such as their proper bandgap, strong light absorption, long ...exciton diffusion length, and easy device fabrication with solution processes, suggesting a great potential for low‐cost, high‐performance solar cells. After a power conversion efficiency (PCE) of 3.8% achieved in 2009, numerous efforts have been made to create PeSCs with high PCEs over 20% in small‐area cells. The next challenge is transition from the lab‐scale spin coating to a large‐scale coating/printing, which will preferably involve the cost‐competitive roll‐to‐roll manufacturing and vacuum‐free full‐printing process. This review provides a progress report on studies related to the scalable deposition methods for PeSCs, such as slot‐die coating, blade coating, spray coating, and various other methods, and to their processing strategies for morphology control in perovskite film formation and discusses the challenges and potential of commercialization of PeSCs in the future.
Many research groups are moving fast to fabricate large‐area perovskite solar cells (PeSCs) and modules by using various printing methods to overcome the limitations of lab‐scale processes and to establish effective manufacturing methods toward roll‐to‐roll mass production. The successful lab‐to‐fab processing translation with the development and progress in the printing technologies will realize the commercialization of PeSCs in the near future.
CH3NH3PbI3-based planar perovskite solar cells were fabricated by slot-die coating, a scalable method. Slot-die coating tends to produce perovskite layers with much lower coverage with overgrown ...crystals than spin coating, which does not include a self-drying mechanism in the process. To mimic the self-drying behavior inherent in spin coating, the present study introduces a blowing step in the slot-die coating method, which significantly improved coverage of the prepared slot-die coated perovskite films. The slot-die-coated device with blowing showed a moderate power conversion efficiency (PCE) of 8.8%. The morphology of the slot-die-coated perovskite film is further improved by optimizing the deposition temperature. The combination of blowing and heating during the slot-die-coating step and the introduction of a printing-friendly hole transport layer resulted in a PCE of 12.7% for the devices fabricated in air.
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•Scalable and roll-to-roll compatible deposition process is developed to produce planar perovskite solarcells.•The highest efficiency from single-step slot die coated perovskite solar cells is achieved.•Synergy effect of gas blowing and heating on morphology of slot die coated films is found.
In photoelectrochemical （PEC） water splitting, charge separation and collection by the electric field in the photoactive material are the most important factors for improved conversion efficiency. ...Hence, ferroelectric oxides, in which electrons are the majority carriers, are considered promising photoanode materials because their high built-in potential, provided by their spontaneous polarization, can signifi＇canfly enhance the separation and drift of photogenerated carriers. In this regard, the PEC properties of BiFeO3 thin-film photoanodes with different crystallographic orientations and consequent ferroelectric domain structures are investigated. As the crystallographic orientation changes from （001）pc via （ll0）pc to （lll）p~, the ferroelastic domains in epitaxial BiFeO3 thin films become mono-variant and the spontaneous polarization levels increase to 110 btC/cm2. Consequent136 the photocurrent density at 0 V vs. Ag/AgC1 increases approximately 5.3-fold and the onset potential decreases by 0.180 V in the downward polarization state. It is further demonstrated that ferroelectric switching in the （lll）pc BiFeO3 thin-film photoanode leads to an approximate change of 8,000% in the photocurrent density and a 0.330 V shift in the onset potential. This study strongly suggests that domain-engineered ferroelectric materials can be used as effective charge separation and collection layers for efficient solar water-splitting photoanodes.
Recently, many kinds of printing processes have been studied to fabricate perovskite solar cells (PeSCs) for mass production. Among them, slot-die coating is a promising candidate for roll-to-roll ...processing because of high-throughput, easy module patterning, and a premetered coating system. In this work, we employed mixed lead precursors consisting of PbAc2 and PbCl2 to fabricate PeSCs via slot-die coating. We observed that slot-die-coated perovskite films based on the mixed lead precursors exhibited well-grown and uniform morphology, which was hard to achieve by using only a single lead source. Consequently, PeSCs made with this precursor system showed improved device performance and reproducibility over single PbAc2. Lastly, a large-area module with an active area of 10 cm2 was fabricated with a power conversion efficiency of 8.3%.
We report organic cation additives in lead iodide solutions as a practical approach for roll-to-roll production of perovskite solar cells. Sequential deposition, which is known to be more reliable ...than 1 step process, is modified to be even more reliable and suitable in roll-to-roll process. Addition of less than stoichiometric amount of organic cations in PbI2 solution effectively improves processability by working as crystallization retardant and make dried PbI2 film more reactive for faster conversion to perovskite. The printing-friendly sequential deposition is used in air with slot die coating, an industrial up-scaling technique, to produce a perovskite solar cell on glass with a 14.4% power conversion efficiency (PCE). The process is then used in actual roll-to-roll machine in air to produce flexible perovskite solar cells with up to 11.0% PCE.
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•Conventional sequential deposition is modified to be more suitable for roll-to-roll process.•Reactive intermediate shows more rapid conversion to perovskite than conventional PbI2 intermediate.•Fully slot die coated perovskite solar cells under ambient condition shows a power conversion efficiency of 14.4%.•Roll-to-roll processed flexible perovskite solar cells show power conversion efficiency of 11%.
Despite the potential of roll-to-roll processing for the fabrication of perovskite films, the realization of highly efficient and reproducible perovskite solar cells (PeSCs) through continuous ...coating techniques and low-temperature processing is still challenging. Here, we demonstrate that efficient and reliable CH3NH3PbI3 (MAPbI3) films fabricated by a printing process can be achieved through synergetic effects of binary processing additives, N-cyclohexyl-2-pyrrolidone (CHP) and dimethyl sulfoxide (DMSO). Notably, these perovskite films are deposited from premixed perovskite solutions for facile one-step processing under a room-temperature and ambient atmosphere. The CHP molecules result in the uniform and homogeneous perovskite films even in the one-step slot-die system, which originate from the high boiling point and low vapor pressure of CHP. Meanwhile, the DMSO molecules facilitate the growth of perovskite grains by forming intermediate states with the perovskite precursor molecules. Consequently, fully printed PeSC based on the binary additive system exhibits a high PCE of 12.56% with a high reproducibility.
A nanostructured micro-prism array (MPA) was integrated onto a solar module consisting of multiple perovskite solar cells (PeSCs) to minimize optical losses from surface reflection and the inactive ...areas reserved for interconnection. The MPA structure redirects light that is incident on inactive areas onto active sub-cell areas to improve the light harvesting efficiency. The nanoscale sub-wavelength structures (SWSs) minimize the surface reflection at the surface of the PeSC module. Combining the technical advantages of these two structures, the MPA decorated with nanoscale SWSs improves the performance of the PeSC module. The short circuit current of the PeSC module employing the MPA decorated with nanoscale SWSs was improved by 1.4 mA/cm2 compared to a conventional PeSC module covered with bare glass.
•A 1 × 4 monolithic perovskite solar cell module was fabricated.•To enhance the light harvesting, the nanostructured MPA was applied onto the module.•The optical characteristics of the nanostructured MPA were analyzed.•The Jsc of the module integrated with nanostructured MPA are relatively improved by 36.8%.
We report a spray deposition technique as a screening tool for solution processed solar cells. A dual-feed spray nozzle is introduced to deposit donor and acceptor materials separately and to form ...blended films on substrates in situ. Using a differential pump system with a motorised spray nozzle, the effect of film thickness, solution flow rates and the blend ratio of donor and acceptor materials on device performance can be found in a single experiment. Using this method, polymer solar cells based on poly(3-hexylthiophene) (P3HT):(6,6)-phenyl C61 butyric acid methyl ester (PC61BM) are fabricated with numerous combinations of thicknesses and blend ratios. Results obtained from this technique show that the optimum ratio of materials is consistent with previously reported values confirming this technique is a very useful and effective screening method. This high throughput screening method is also used in a single-feed configuration. In the single-feed mode, methylammonium iodide solution is deposited on lead iodide films to create a photoactive layer of perovskite solar cells. Devices featuring a perovskite layer fabricated by this spray process demonstrated a power conversion efficiencies of up to 7.9%.
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