Differentially pumped spray deposition as a rapid screening tool for organic and perovskite solar cells

The first demonstration of entirely roll-to-roll fabricated perovskite solar cell modules under ambient room conditions

The rapid development of organic-inorganic hybrid perovskite solar cells has resulted in laboratory-scale devices having power conversion efficiencies that are competitive with commercialised technologies. However, hybrid perovskite solar cells are yet to make an impact beyond the research community, with translation to large-area devices fabricated by industry-relevant manufacturing methods remaining a critical challenge. Here we report the first demonstration of hybrid perovskite solar cell modules, comprising serially-interconnected cells, produced entirely using industrial roll-to-roll printing tools under ambient room conditions. As part of this development, costly vacuum-deposited metal electrodes are replaced with printed carbon electrodes. A high-throughput experiment involving the analysis of batches of 1600 cells produced using 20 parameter combinations enabled rapid optimisation over a large parameter space. The optimised roll-to-roll fabricated hybrid perovskite solar cells show power conversion efficiencies of up to 15.5% for individual small-area cells and 11.0% for serially-interconnected cells in large-area modules. Based on the devices produced in this work, a cost of ~0.7 USD W-1 is predicted for a production rate of 1,000,000 m² per year in Australia, with potential for further significant cost reductions.

Orthogonal Printable Reduced Graphene Oxide 2D Materials as Hole Transport Layers for High-Performance Inverted Polymer Solar Cells: Sheet Size Effect on Photovoltaic Properties

Creating an orthogonal printable hole-transporting layer (HTL) without damaging the underlying layer is still a major challenge in fabricating large-area printed inverted polymer solar cells (PSCs). In this study, we prepared orthogonal-processable fluorine-functionalized reduced graphene oxide (FrGO) series with various two-dimensional sheet sizes such as large-sized FrGO (1.1 μm), medium-sized FrGO (0.7 μm), and small-sized FrGO (0.3 μm) and systematically investigated the size effect of FrGOs on the hole transport properties of PSCs. The FrGOs exhibit highly stable dispersion without change over 90 days in 2-propanol solvent, indicating very high dispersion stability. Decreasing the sheet size of FrGOs enhanced hole-transporting properties, resulting in power conversion efficiencies (PCEs) of 9.27 and 9.02% for PTB7-Th:EH-IDTBR- and PTB7-Th:PC₇₁BM-based PSCs, respectively. Compared to devices with solution-processed poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS), a 14% enhancement of PCEs was achieved. Interestingly, the PCEs of devices with the smallest FrGO sheet are higher than the PCE of 8.77% of a device with vacuum-deposited MoO₃. The enhancement in the performance of PSCs is attributed to the enhanced charge collection efficiency, decreased leakage current, internal resistance, and minimized charge recombination. Finally, small-sized FrGO HTLs were successfully coated on the photoactive layer using the spray coating method, and they also exhibited PCEs of 9.22 and 13.26% for PTB7-Th:EH-IDTBR- and PM6:Y6-based inverted PSCs, respectively.

Scalable Ultrasonic Spray-Processing Technique for Manufacturing Large-Area CH3NH3PbI3 Perovskite Solar Cells

Organic-inorganic hybrid perovskite solar cells are on the brink of a breakthrough in photovoltaic technology. Scale-up and large-area processing have become the focal points that must be resolved before commercialization. In this study, the scalable ultrasonic spray deposition method for high-throughput coating of the perovskite photoactive layer with a large active area of up to 3 cm² is implemented by precisely controlling the concentration of the precursor solution and spray passes. CH₃NH₃PbI₃ films with large crystallites and a suitable thickness of ∼350 nm are facilely developed through one-step direct ultrasonic spraying. Less hysteresis and highly reproducible power conversion efficiencies (PCEs) of up to 12.30% (11.43 ± 0.43% on average for 20 devices) are achieved by an optimized single-junction device with an active area of 1 cm², along with good ambient stability. The device retained ∼80 and ∼65% of the initial PCE after 60 and 105 days in ambient, respectively. The ultrasonic spray-coated perovskite solar cells can be further scaled to larger areas of 2 and 3 cm² and exhibit PCEs of 10.18 and 7.01%, respectively. The reliable scale-up process for manufacturing the atmospheric wet-coated perovskite film is available in cost-effective and easily operated bench-top variants to bridge the interconnection between applied research and industry.

Perovskite solar cells in N-I-P structure with four slot-die-coated layers

The fabrication of perovskite solar cells in an N-I-P structure with compact titanium dioxide blocking, mesoporous titanium dioxide scaffold, single-step perovskite and hole-transport layers deposited using the slot-die coating technique is reported. Devices on fluorine-doped tin oxide-coated glass substrates with evaporated gold top contacts and four slot-die-coated layers are demonstrated, and best cells reach stabilized power conversion efficiencies of 7%. This work demonstrates the suitability of slot-die coating for the production of layers within this perovskite solar cell stack and the potential to transfer to large area and roll-to-roll manufacturing processes.

Perovskite solar cells in N-I-P structure with four slot-die-coated layers

The fabrication of perovskite solar cells in an N-I-P structure with compact titanium dioxide blocking, mesoporous titanium dioxide scaffold, single-step perovskite and hole-transport layers deposited using the slot-die coating technique is reported. Devices on fluorine-doped tin oxide-coated glass substrates with evaporated gold top contacts and four slot-die-coated layers are demonstrated, and best cells reach stabilized power conversion efficiencies of 7%. This work demonstrates the suitability of slot-die coating for the production of layers within this perovskite solar cell stack and the potential to transfer to large area and roll-to-roll manufacturing processes.

One-Step Printable Perovskite Films Fabricated under Ambient Conditions for Efficient and Reproducible Solar Cells

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.

Controlled Deposition and Performance Optimization of Perovskite Solar Cells Using Ultrasonic Spray-Coating of Photoactive Layers

This study investigated a new film-deposition technique, ultrasonic spray-coating, for use in the production of a photoactive layer of perovskite solar cells. Stable atomization and facile fabrication of perovskite thin films by ultrasonic spray-coating were achieved in a one-step method through manipulating the ink formulation (e.g., solution concentration, precursor composition, and mixing solvent ratio) and the drying kinetics (e.g., post-annealing temperature). The performance of the perovskite solar cells was mainly influenced by the intrinsic film morphology and crystalline orientation of the deposited perovskite layer. By suitable optimization of the spreading and drying conditions of the ink, ultrasonic spray-coated perovskite photovoltaic devices were obtained with a maximum power conversion efficiency of 11.30 %, a fill factor of 73.6 %, a short-circuit current of 19.7 mA cm^-1 , and an open-circuit voltage of 0.78 V, respectively. Notably, the average power efficiency reached above 10 %, attributed to the large flower-like perovskite crystal with orientation along the (1 1 2)/(2 0 0) and (2 2 4)/(4 0 0) directions. Thus, the ultrasonic spray-coating method for perovskite photoactive layers, combining advantages of good photovoltaic performance results and benefits from cost and processing, has the potential for large-scale commercial production.