Coated and Printed Perovskites for Photovoltaic Applications

Abstract

optoelectronic devices, a novel lowcost and highly efficient photovoltaic (PV) material emerged. Only 10 years after the first reported perovskite solar cells (PSCs), power conversion efficiencies (PCEs) above 23% were certified, exceeding those of much longer established thin-film PV technologies, including organic photovoltaics (OPV) and inorganic thin-film PV based on copper indium gallium selenide (CIGS) or cadmium telluride (CdTe). [1] The material class of hybrid organic-inorganic perovskites combines excellent optoelectronic properties, such as long diffusion lengths [2] and short absorption lengths, [3] with the ease of solution processing, low energy payback times, and low-cost precursor materials. [4] Moreover, the optoelectronic properties and the material stability can be engineered by varying the constituents in the perovskite crystal structure ABX 3 . For example, the bandgap (E G ) can be tuned by changing the stoichiometric ratio of Br and I at the halogen anion site X. [5][6][7] In order to improve the stability of hybrid organic-inorganic perovskites, compositional engineering of the cation site A was demonstrated to be successful via combining methylammonium (CH 3 NH 3 + or MA + ), formamidinium (CH 5 N 2 + or FA + ), Cs + , and Rb + ions in the so-called multi-cation perovskites. [8][9][10][11] Three key challenges hinder today the economical breakthrough of PSCs:Stability: First, the instability of PSCs against moisture, oxygen, light, and temperature limits the lifetime of PSCs to a fraction of the warranty lifetime (often >25 years) of the market dominating crystalline silicon (c-Si) PV. [12] Very respectable progress has been made over recent years to enhance the stability of PSCs by demonstrating stability over 1000 h, but significant further advances in terms of stability are needed to lift the technology to a level where it is ready to compete with, or be a bolt-on tandem companion to the current PV heavyweight of c-Si. A number of reviews cover recent developments on the topic of stability. [13][14][15][16][17] Toxicity: Second, highly efficient PSCs still contain lead, the toxicity of which hampers the acceptance of the technology and could conflict with legislative barriers. [18] Other recent reviews present progress with respect to this challenge. [19,20] Upscaling: Third, the upscaling of perovskite PV devices to commercial PV module sizes (>1 m 2 ) must be achieved. To date, the vast majority of research and development of PSCs is still Hybrid organic-inorganic metal halide perovskite semiconductors provide opportunities and challenges for the fabrication of low-cost thin-film photovoltaic devices. The opportunities are clear: the power conversion efficiency (PCE) of small-area perovskite photovoltaics has surpassed many established thin-film technologies. However, the large-scale solution-based deposition of perovskite layers introduces challenges. To form perovskite layers, precursor solutions are coated or printed and these must then be crystallized into the perovskite structur...

Inkjet‐Printed Micrometer‐Thick Perovskite Solar Cells with Large Columnar Grains

“…Despite the progress on IJP PSCs, the PCEs and stable power outputs of these devices lack significantly behind the state‐of‐the‐art spin‐coated PSCs . To date, the progress on IJP PSCs has been largely based on adapted recipes and process parameters from spin‐coated PSCs, for example, with regard to precursor systems, device architecture, and annealing procedures .…”

“…Throughout the detailed characterization of the underlying nickel oxide (NiO x ) layer the stabilized PCE has been published earlier this year . The demonstrated short‐circuit current density ( J SC ) of these IJP PSCs is in the range of the highest J SC reported for spin‐coated PSCs of similar architecture and same band gap as well as, to the authors' best knowledge, considerably higher than any IJP PSCs . This improvement originates from exceptionally thick absorber layers, compared to state‐of‐the‐art spin‐coated and excellent charge carrier lifetimes.…”

Laminated Perovskite Photovoltaics: Enabling Novel Layer Combinations and Device Architectures

“…The widely tunable bandgap of these perovskites by compositional variations of the halide anion in the perovskite crystal structure allows strong light absorption in a broad spectral range . With their low material costs and a wide range of possible deposition techniques, perovskites qualify as promising candidates for next‐generation multi‐junction PV . Moreover, combined with established PV technologies, like wafer‐based silicon or copper indium gallium selenide films, perovskite‐based tandems are currently the most promising technology for terrestrial PV to enable PCEs exceeding the single‐junction Shockley–Queisser limit …”

Fully Spray-Coated Triple-Cation Perovskite Solar Cells

“…Currently most perovskite device optimisation is performed using spin coating; a simple and reliable technique capable of producing highly uniform thin films. However spin coating is usually only suitable for coating small substrates on the order of square centimetres, rather than square meters 10 . Spin coating is also a wasteful coating process, as the majority of the ink to be coated is thrown from the substrate during deposition.…”

“…Furthermore spray deposition has been utilised to probe compositional space in mixed cation systems by controlling the flow of two inks delivered to the spray head prior to atomisation 24,25 . The interested reader is directed to a recent review that charts the development of spray-coated perovskite PV 10 .…”