Pinhole-free Films Research Articles

Enhancing Stability in All-Vacuum-Evaporated Hybrid Perovskite Solar Cells via a Bipolar Host as a Hole-Transporting Layer.

Growing an ultrathin hybrid organic-inorganic perovskite film while maintaining high efficiency and addressing photostability challenges for commercial devices remains a significant hurdle. In this study, we explore the incorporation of organometallic copper phthalocyanine (CuPc) and MS-OC (a previously published spiro-based interfacial material for perovskite solar cells (PSCs), featuring an ortho-oriented carbazole donor) as an addition to the hole-transporting layer (HTL) in all-vacuum-deposited Cs0.06FA0.94Pb(I0.68Br0.32)3 PSCs. By innovatively introducing a 3 nm-thin MS-OC layer at the CuPc-perovskite interface, we achieve a deeper understanding of the crystallographic dynamics of perovskites, resulting in a uniform and pinhole-free film. We demonstrate that PSCs utilizing the CuPc HTL with an MS-OC interfacial layer in a p-i-n architecture achieve a power conversion efficiency (PCE) of up to 14.42%. Remarkably, the CuPc/MS-OC-based device exhibits outstanding long-term photostability, maintaining its initial PCE over 400 h (T100 = 400 h) under continuous sunlight illumination. By configuring the device architecture as ITO/MoO3/CuPc/MS-OC/perovskite/C60/BCP/Ag, we find that the evaporated MS-OC thin films effectively reduce nonradiative losses, passivate the perovskite, and enhance device performance. Our findings indicate that the polarity of the underlying surface significantly influences perovskite nucleation, underscoring the potential to improve photostability by controlling interfacial imperfections.

Precursor Ink Engineering to Implement Vacuum Extraction Method for Scalable Production of Perovskite Solar Cells.

Engineering perovskite precursor ink to widen the processing window is crucial to obtaining uniform, compact, and pinhole-free perovskite films at scale using industrially relevant solution coating techniques. Here, we introduce a ternary solvent system and systematically investigate the impacts of coordinating solvents, N-methyl-2-pyrrolidone (NMP) and N,N'-dimethylpropyleneurea (DMPU), on the physical properties of the slot-die-coated perovskite films and on the corresponding device performance. Tailoring NMP and DMPU concentrations in the precursor ink allows us to control the perovskite intermediate phase formation and widen the processing window, enabling the reproducible production of perovskite films with high photoelectrical quality at scale. Using the optimized precursor ink, we demonstrate slot-die-coated perovskite minimodules with power conversion efficiencies of 19 and 16% on 56 and 100 cm2 substrates, respectively.

Intercalation Electrode and Grain Reconstruction Induce Significant Sensitivity Enhancement for Perovskite X-ray Detectors.

Organic-inorganic hybrid perovskites have been recognized as potential candidates in direct X-ray detectors and have triggered tremendous interest in the past years. The blade coating method meets the requirements of large area and low cost for perovskite X-ray detectors, while the low compactness resulting from solvent evaporation limits the charge collection efficiency (CCE) and device sensitivity. Most of the reports are focused on the melioration of perovskite films to increase device sensitivity; there are still problems of low CCE. Herein, we introduce an intercalation-electrode device structure and achieve a ∼20-fold sensitivity enhancement. Carrier distribution throughout the thick films is simulated, and the electrode intercalating site can be optimized according to the mobility-lifetime factor to achieve the highest CCE. A methylamine thiocyanate (MASCN) additive-assisted coating strategy is developed, and pinhole free thick films with regrown particles are obtained without frequently used hot/soft pressing. A sensitivity level of ∼105 μC Gyair-1 cm-2 as well as a detection limit of 77 nGyair s-1 is achieved under low bias, which is among the best performance for polycrystalline perovskite direct X-ray detectors. This work provides a universal device structure design to overcome carrier loss through a long transport distance and enhances the CCE for ultrahigh sensitivity.

Bottom Contact Engineering for Ambient Fabrication of >25% Durable Perovskite Solar Cells.

The bottom contact in perovskite solar cells (PSCs) is easy to cause deep trap states and severe instability issues, especially under maximum power point tracking (MPPT). In this study, sodium gluconate (SG) is employed to disperse tin oxide (SnO2) nanoparticles (NPs) and regulate the interface contact at the buried interface. The SG-SnO2 electron transfer layer (ETL) enabled the deposition of pinhole-free perovskite films in ambient air and improved interface contact by bridging effect. SG-SnO2 PSCs achieved an impressive power conversion efficiency (PCE) of 25.34% (certified as 25.17%) with a high open-circuit voltage (VOC) exceeding 1.19V. The VOC loss is less than 0.34V relative to the 1.53eV bandgap, and the fill factor (FF) loss is only 2.02% due to the improved contact. The SG-SnO2 PSCs retained around 90% of their initial PCEs after 1000h operation (T90 = 1000h), higher than T80 = 1000h for the control SnO2 PSC. Microstructure analysis revealed that light-induced degradation primarily occurred at the buried holes and grain boundaries and highlighted the importance of bottom-contact engineering.

Influence of interfacial roughness on slot-die coatings for scaling-up high-performance perovskite solar cells

Slot-die coating (SDC) technology is a potential approach to mass produce large-area, high-performance perovskite solar cells (PSCs) at low cost. However, when the interface in contact with the perovskite ink has low wettability, the SDC cannot form a uniform pinhole-free perovskite film, which reduces the performance of the PSC. To address this issue, in this study, the wettability of the hole transport layer (HTL) interface was investigated in depth by analyzing the variation of wettability with process and its correlation with the roughness of the HTL interface. As a result, it was found that SDC could increase the roughness of the HTL interface to improve wettability and form a uniform high-quality perovskite layer without pinholes, and furthermore, SDC-based NiOx/Me-4PACz HTL suppressed energy losses at the HTL/perovskite interface. In addition, a unit cell achieved 19.17% of efficiency with long-term stability and lab cell-sized modules showed up to 17.42%.

Comparative studies on pinhole free CBD-CdZnS thin films on ITO and FTO substrate

The development of CdZnS thin films using the chemical bath deposition process in nonaqueous media is a technological challenge. In this work, 75 millilitres of ethylene glycol and ethanol (1:2 ratios) were used to develop a CdZnS thin film on ITO and FTO glass substrates using cadmium acetate, zinc sulphate, and thiourea. The ideal bath temperature was kept at 1300C and the anneal temperature of the film that had been deposited in the air was maintained at 3500C. The films have been examined using FTIR, WCA, FESEM, and XRD. XRD studies reveal that CdZnS films have a hexagonal crystal structure with a preference for orientation (002) during the deposition and annealing processes and the assessment of the various attributes have been done, such as dislocation density, micro strain, and grain size. FESEM study indicates that as deposited film on ITO glass have smooth surface and grains appear in the form of small needle shape of equal sizes where as FTO substrate reveals the grains of equal size throughout the entire surface in cluster form. It is also confirmed that both the CdZnS films formed on ITO and FTO substrates have hydrophilic quality. The presence of chemical bonds and functional groups was confirmed by FTIR analysis.

Collaborative Fabrication of High-Quality Perovskite Films for Efficient Solar Modules through Solvent Engineering and Vacuum Flash System.

The vacuum flash solution method has gained widespread recognition in the preparation of perovskite thin films, laying the foundation for the industrialization of perovskite solar cells. However, the low volatility of dimethyl sulfoxide and its weak interaction with formamidine-based perovskites significantly hinder the preparation of cell modules and the further improvement of photovoltaic performance. In this study, we describe an efficient and reproducible method for preparing large-scale, highly uniform formamidinium lead triiodide (FAPbI3) perovskite films. This is achieved by accelerating the vacuum flash rate and leveraging the complex synergism. Specifically, we designed a dual pump system to accelerate the depressurization rate of the vacuum system and compared the quality of perovskite film formed at different depressurization rates. Further, to overcome the limitations posed by DMSO, we substituted N-methylpyrrolidone as the ligand solvent, creating a stable intermediate complex phase. After annealing, it can be transformed into a uniform and pinhole-free FAPbI3 film. Due to the superior quality of these films, the large area perovskite solar module achieved a power conversion efficiency of 22.7% with an active area of 21.4 cm2. Additionally, it obtained an official certified efficiency of 22.1% with an aperture area of 22 cm2, and it demonstrated long-term stability.

Towards the fabrication of flexible thin film CdTe solar cells: The significance of substrate surfaces

Thin film CdTe solar cells have been recognized as reliable alternative for the manufacture of cheap photovoltaic solar cells of the future, due to its excellent absorber characteristics and simple, low-cost manufacturability. However, for the attainment of higher cell performances, additional studies are needed to increase cell efficiency through further development of better quality films and new fabrication processes. In the substrate-structured CdTe thin film solar cells, the CdTe absorber layer is deposited directly onto the substrate or through a back contact layer. But the quality of deposited film is believed to depend on the type and smoothness of the substrate. In this work CdTe was deposited on different substrates by RF sputtering and the effects on the deposited films were studied in terms of their structural and morphological forms. The substrates used were: pure molybdenum sheets (Mo), molybdenum-sputtered on molybdenum (Mo/Mo), molybdenum-sputtered polyimide (PI/Mo) and molybdenum-sputtered glass (glass/Mo). The characterization tools used included XRD, SEM and AFM. The results showed that all surfaces produced uniform, compact and pinhole-free films; however, those on smoother surfaces produced larger as-deposited grain sizes of up to1.7μm as against 1.3 for rougher surfaces. Non-uniformities such as overgrowth and voids were observed, but only films on PI showed evidence of cracking and peel-offs.

Ammonium Sulfate to Modulate Crystallization for High-Performance Rigid and Flexible Perovskite Solar Cells.

Perovskite solar cells (PSCs) are attracting widespread research and attention as highly promising candidates in the field of electronic photovoltaics owing to their exceptional power conversion efficiency (PCE). However, rigid or flexible PSCs still face challenges in preparing full-coverage and low-defect perovskite films, as well as achieving highly reproducible and highly stable devices. Herein, a multifunctional additive 2-aminoethyl hydrogen sulfate (AES) is designed to regulate the film crystallization and thereby form flat and pinhole-free perovskite films. It is found that the introduction of AES can effectively passivate defects, restrain charge carrier recombination, and then achieve a higher fill factor. As seen with grazing incidence wide-angle X-ray scattering (GIWAXS), this approach does not affect the crystal orientation distribution. It is observed that AES addition shows a universality across different perovskite components since the PCE is improved up to 20.7% for FA0.97MA0.03Pb(I0.97Br0.03)3-AES, 22.85% for Cs0.05FA0.95PbI3-AES, 22.23% for FAPbI2.7Br0.3-AES, and 23.32% for FAPI-AES rigid devices. Remarkably, the non-encapsulated flexible Cs0.05 (FA0.85MA0.15)0.95Pb(I0.85Br0.15)3 device with AES additive delivers a PCE of 20.1% and maintains over 97% of its initial efficiency under ambient conditions (25±5% relative humidity) over 2280h of aging.

Fluorinated paracyclophane dimers for polymeric thin films via chemical vapor polymerization

Poly(para-xylylene) thin films from Gorham method via chemical vapor polymerization (CVP) process (so called Parylene) have been extensively utilized in various application fields. Specific functional groups can be also introduced into thin polymeric films via CVP process using functionalized paracyclophane dimer. There have been numerous efforts to fabricate parylene thin films using synthesized and functionalized paracyclophane dimers so far. Herein we report on synthesis of fluorine containing paracyclophane dimers and their polymeric thin films via Gorham method. Three different types of fluorine containing paracyclophane derivatives are synthesized and the CVP thin films are prepared in all cases by adjusting processing condition. Even though the functional groups on parylene thin films are similar, dramatic differences in surface energy can be observed. This work can provide extended material choices for whom want to precisely control surface properties with robust, pin-hole free, and conformal coatable polymeric thin films.

Hot-Antisolvent Assisted Morphological Regulation of Perovskites for Semitransparent Photovoltaics Employing Hot-Pressing Approach

The processing of halide perovskites in the air significantly influences their morphology and surface coverage, often leading to the presence of numerous trap densities that adversely affect device performance. In this study, we explored the development of perovskite films using a solvent extraction method, where the temperature of the anisole antisolvent was varied. Our findings demonstrate that the hot-antisolvent strategy effectively controls nucleation, resulting in the formation of highly dense, pinhole-free, and crack-free perovskite films with reduced surface roughness. Films fabricated using this hot-antisolvent approach exhibited enhanced photoluminescence, indicating lower trap density and increased recombination resistance. They also showed slower charge carrier recombination rates and efficient charge extraction, suggesting the suppression of nonradiative recombination. Furthermore, the superior quality of perovskite films obtained through the hot-antisolvent strategy significantly enhanced the power conversion efficiency (PCE) of hot-pressed semitransparent perovskite solar cells. The PCE remarkably increased from 0.13% to an impressive 12.65% while maintaining an average visible transmittance of 26.55% and exceptional air stability for 2000 hours with no significant degradation in initial PCE. This study achieves a record-breaking light utilization efficiency of 3.36% in the realm of research on hot-press processes.

Volatile Perovskite Precursor Ink Enables Window Printing of Phase-Pure FAPbI3 Perovskite Solar Cells and Modules in Ambient Atmosphere.

Despite the great success of perovskite photovoltaics in terms of device efficiency and stability using laboratory-scale spin-coating methods, the demand for high-throughput and cost-effective solutions remains unresolved and rarely reported because of the complicated nature of perovskite crystallization. In this work, we propose a stable precursor ink design strategy to control the solvent volatilization and perovskite crystallization to enable the wide speed window printing (0.3 to 18.0 m/min) of phase-pure FAPbI3 perovskite solar cells (pero-SCs) in ambient atmosphere. The FAPbI3 perovskite precursor ink uses volatile acetonitrile (ACN) as the main solvent with DMF and DMSO as coordination additives is beneficial to improve the ink stability, inhibit the coffee rings, and the complicated intermediate FAPbI3 phases, delivering high-quality pin-hole free and phase-pure FAPbI3 perovskite films with large-scale uniformity. Ultimately, small-area FAPbI3 pero-SCs (0.062 cm2 ) and large-area modules (15.64 cm2 ) achieved remarkable efficiencies of 24.32 % and 21.90 %, respectively, whereas the PCE of the devices can be maintained at 23.76 % when the printing speed increases to 18.0 m/min. Specifically, the unencapsulated device exhibits superior operational stability with T90 >1350 h. This work represents a step towards the scalable, cost-effective manufacturing of perovskite photovoltaics with both high performance and high throughput.

The synergistic effect of dry air and surfactants enables water to be a promising green solvent for stable and efficient perovskite solar cells

Through the synergistic effect of dry air and surfactants, high-quality, pinhole free perovskite films prepared from aqueous inks (Pb(NO3)2/H2O) can be easily obtained.

Phase-engineering compact and flexible CsPbBr3 microcrystal films for robust X-ray detection.

All-inorganic CsPbBr3 perovskites have gained significant attention due to their potential in direct X-ray detection. The fabrication of stable, pinhole-free thick films remains challenging, hindering their integration in durable, large-area high-resolution devices. In this study, we propose a facile strategy using a non-conductive polymer to create a flexible, compact thick film under ambient conditions. Furthermore, we investigate the effect of introducing the 2D CsPb2Br5 phase into CsPbBr3 perovskite crystals on their photophysical properties and charge transport. Upon X-ray exposure, the devices consisting of the dual phase exhibit improved stability and more effective operation at higher voltages. Rietveld refinement shows that, due to the presence of the second phase, local distortions and Pb-vacancies are introduced within the CsPbBr3 lattice. This in turn presumably increases the ion migration energy barrier, resulting in a very low dark current and hence, enhanced stability. This feature might benefit local charge extraction and, ultimately, the X-ray image resolution. These findings also suggest that introducing a second phase in the perovskite structure can be advantageous for efficient photon-to-charge carrier conversion, as applied in medical imaging.

Influences of deposition conditions on atomic layer deposition films for enhanced performance in perovskite solar cells

Atomic layer deposition (ALD) is a key technology for fabricating functional layers in perovskite solar cells, as it can deposit pinhole-free films with atomic-level thickness and tunable composition on high-aspect-ratio surfaces. Various deposition conditions have significant effects on the growth, physical, and chemical properties of ALD films, which, in turn, critically influences the performance of associated devices. Here, we review the reaction mechanisms underlying ALD and summarize how variables, such as precursors, deposition temperatures, and substrates, impinge upon the quality of ALD films and the related devices. We emphasize the role of substrate in determining the nucleation and growth behavior of ALD films, which has been overlooked in previous reviews. Finally, we highlight the potential application of ALD in efficient perovskite solar cells in terms of carrier transport, encapsulated, and buffer layers, especially for tandem cells.

Atomic Layer Deposition of LixCoyOz Cathodic Thin Films for Li-Ion Batteries

Atomic-Layer Deposition (ALD) is an appealing gas-phase technique for the deposition of thin solid cathodic films for 2D and especially 3D Li-ion microbatteries (Li-ion MBs). ALD relies on surface chemistry reactions and allows the fabrication of ultrathin pinhole free solid films with well controlled thickness, continuity and conformality. It has been shown to successfully cover 3D complex shapes for various applications including Li-ion MBs. Yet, a fairly low amount of work has been published on the realization by ALD of such cathodic active thin films. Typical cathodic materials are at least ternary compounds (including Lithium) which call for supercycles or multilayers approaches to synthesize them by ALD. As reminded for example by Maximov M. et al 1, the use of lithiated precursors complexifies the ALD fabrication due to, among others, Lithium high diffusivity and reactivity. In the case of LiCoO2 ALD synthesis for example, the only reported work to date is the one of Donders et al. 2 where the authors used CoCp2/LiOtBu as Cobalt/Lithium precursors respectively and O2 plasma as the oxidizing agent.The talk will describe the synthesis and characterizations of the LixCoyOzthin filmspreparedby a thermal ALD approach. It will detail the supercycle methods used as well as some of the investigations performed to explore the chemistry of the deposited films (Raman spectroscopy, X-Ray Photoelectron Spectroscopy, X-Ray Diffraction and Energy Dispersive X-Ray). The electrochemical performances of the films will also be shared and compared with the State of the art. 1 Maximov, M.; Nazarov, D.; Rumyantsev, A.; Koshtyal, Y.; Ezhov, I.; Mitrofanov, I.; Kim, A.; Medvedev, O.; Popovich, A. Atomic Layer Deposition of Lithium–Nickel–Silicon Oxide Cathode Material for Thin-Film Lithium-Ion Batteries. Energies 2020, 13, 2345. 2 Donders, M. E., ArnoldBik, W. M., Knoops, H. C. M., Kessels, W. M. M., & Notten, P. H. L. (2013). Atomic layer deposition of LiCoO2 thin film electrodes for all-solid-state Li-ion micro-batteries. Journal of the Electrochemical Society, 160(5), A3066-A3071.

(Invited) Processing of Perovskite Materials for Optoelectronic Devices

Among materials used for thin film technologies, perovskite materials have emerged as one of the rising stars for optoelectronic applications. They show great promise for several applications like e.g. photovoltaics, lasers, light emitting diodes or X-ray detectors. Their success is founded on the feature of some perovskite materials to be largely tolerant to the formation of defects, which enables functional layer deposition from liquid precursor inks. In order to exploit the extraordinary optoelectronic properties, it is necessary to adapt the material processing to the requirements of the application. For a large spectrum of devices, homogeneous, high quality, large grain poly-crystalline perovskite layers are required. Accordingly, our work strives to cover the whole spectrum of the layer formation ranging from the perovskite precursor ink chemistry, the deposition process to post-processing and re-crystallization.Regarding the precursor ink, we spotlight the complex formation of the lead halide species by nuclear magnetic resonance and electrical conductivity measurements. We found a strong and systematic impact of the choice of (Lewis base) solvent on the formation of lead complexes in the precursor solution. Surprisingly, a strong difference in the complex formation, not necessarily translates to notable differences in the resulting layers. Indeed, the difference observed in solvation and coordination appears to become less for increased concentrations of the precursor ink. As such we assume, that throughout the drying process, the impact of lead-solvent complexes observed in the ink might diminish. To add another parameter, we also included Lewis-base additives into our investigations, that evidently modify the shape and size of the crystallites in the resulting layers. Despite their far higher donor number, we found the additive to only marginally impact on the lead core in the liquid precursor. Rather, by in-situ GIWAXS characterization, we could show that the intake of thermal energy during the annealing process proves crutial for changes in the crystal formation. After a gas-quenching process, where the perovskite phase is already present, the formation process with and without additive did not show notable differences. Subsequent thermal annealing of the deposited layers on the other hand allows the coordination between lead and the additive and affords a re-organization of the perovskite phase. During the deposition process, anyhow, the process technology (like gas quenching) is still important to form a homogeneous and pinhole-free initial film, which then can reorganize to form a high-quality perovskite layer.In the second part of the presentation, we will show, that the strategy of thermally assisted reorganization is not limited to the initial annealing step. By using a thermal hot-pressing process, we are also able to trigger the perovskite re-organization and re-crystallization even if the perovskite deposition and formation process is already finished. We performed post-processing by providing thermal energy, while simultaneously limiting the available space where potential perovskite decomposition products could leak, by pressing it with a flat stamp. As a result, the perovskite recrystallizes and forms extremely smooth layers that comprise large grains and express remarkable optical quality. We show this strategy to be applicable to a large variety of different hybrid as well as all-inorganic perovskite materials. Employing patterned stamps, we also utilize this strategy to directly imprint photonic nanostructures (e.g. Bragg gratings) into the perovskite layers.We will show how additive driven reorganization and thermal imprint enable a variety of optoelectronic devices ranging from light harvesting (single-junction and tandem perovskite based solar cells) to stimulated light emission (perovskite lasers).

Iodonium Initiators: Paving the Air-free Oxidation of Spiro-OMeTAD for Efficient and Stable Perovskite Solar Cells.

To date, perovskite solar cells (pero-SCs) with doped 2,2',7,7'-tetrakis(N,N-di-p-methoxyphenylamine)-9,9'-spirobifluorene (Spiro-OMeTAD) hole transporting layers (HTLs) have shown the highest recorded power conversion efficiencies (PCEs). However, their commercialization is still impeded by poor device stability owing to the hygroscopic lithium bis(trifluoromethanesulfonyl)imide and volatile 4-tert-butylpyridine dopants as well as time-consuming oxidation in air. In this study, we explored a series of single-component iodonium initiators with strong oxidability and different electron delocalization properties to precisely manipulate the oxidation states of Spiro-OMeTAD without air assistance, and the oxidation mechanism was clearly understood. Iodine (III) in the diphenyliodonium cation (IP+ ) can accept a single electron from Spiro-OMeTAD and forms Spiro-OMeTAD⋅+ owing to its strong oxidability. Moreover, because of the coordination of the strongly delocalized TFSI- with Spiro-OMeTAD⋅+ in a stable radical complex, the resulting hole mobility was 30 times higher than that of pristine Spiro-OMeTAD. In addition, the IP-TFSI initiator facilitated the growth of a homogeneous and pinhole-free Spiro-OMeTAD film. The pero-SCs based on this oxidizing HTL showed excellent efficiencies of 25.16 % (certified: 24.85 % for 0.062-cm2 ) and 20.71 % for a 15.03-cm2 module as well as remarkable overall stability.

Green N1 additive modified perovskite precursor enables effective manufacturing of large-area solar cell modules with high efficiency and stability

Although the record power conversion efficiency (PCE) of perovskite solar cells (PSCs) has been continuously boosted, the effective large-area manufacturing and good device stability are the major challenges toward their commercialization. Here, we report a green additive of N-methyl-2-piperidone (N1) to modify the perovskite precursor, enabling the one-step fabrication of high-quality large-area perovskite films with enhanced PCE and stability. The results show that due to the stronger complexation ability of N1 additive with PbI2, the generated PbI2-N1 complex can effectively control the nucleation and growth of perovskite to realize lead halide-framework template-assistant crystallization reaction with organic cation in the one-step solution preparation of (FAPbI3)0.95(MAPbBr3)0.05, leading to the homogeneous pinhole-free perovskite films with few defects. Therefore, the PSC device with small active-area of 0.09 cm2 exhibits an efficiency of 23.2 %. Moreover, highly efficient slot-die printed 5 × 5 cm2 PSC module has been obtained with a champion PCE of 21 % and improved device stability over 1000 h. This work demonstrates a new strategy to realize high-quality large-scale perovskite films for solution-processed PSC modules, which may be further improved and extended to other kinds of PSCs and applications such as perovskite light-emitting diodes and detectors.

Large-scale efficient mid-wave infrared optoelectronics based on black phosphorus ink

The mid-wave infrared (MWIR), ranging from 2 to 5 micrometers, is of substantial interest for chemical sensing, imaging, and spectroscopy. Black phosphorus (bP)–based MWIR light emitters and detectors have been shown to outperform the state-of-the-art for commercial devices due to the low Auger recombination coefficient of bP. However, the scalability of these devices remains a challenge. Here, we report a bP ink formula that preserves the exceptional MWIR optoelectronic properties of bP to deposit centimeter-scale, uniform, and pinhole free films with a photoluminescence quantum yield higher than competing III-V and II-VI semiconductors with similar bandgaps at high excitation regime. As a proof of concept, we use bP ink as a “phosphor” on a red commercial light-emitting diode to demonstrate bright MWIR light emission. We also show that these films can be integrated into heterostructure device architectures with electron and hole selective contacts for direct-injected light emission and detection in MWIR.