Are perovskite LEDs about to take off? The lifespan challenge has been solved—these three technologies are the most promising.

Recently, I came across a pretty interesting study on perovskite light-emitting diodes. You might not have heard of them yet, but they actually hold tremendous potential—matching the luminous efficiency of today’s widely used LEDs, while also being cost-effective and delivering pure, vibrant colors. However, there’s one major challenge: their lifespan is still too short, making large-scale applications impossible for now. Today, I’ll break it down for you step by step, explaining exactly what makes these devices so tricky—and what solutions are currently being explored to overcome these hurdles.

Let me first briefly introduce the background of this material. Perovskite materials aren’t new—they were discovered long ago—but it wasn’t until 2014 that someone successfully created a light-emitting diode using them. In recent years, research in this field has advanced rapidly. Today, perovskite LEDs capable of emitting red, green, and blue light have achieved peak luminous efficiencies approaching 30%, which is already quite competitive with commercial LED technologies. However, while efficiency has improved significantly, device lifespan remains a major challenge. Currently, LED lifespan is typically measured using an indicator called T50—the time it takes for brightness to drop to half its initial level. Can you guess how much the lifespans differ among LEDs emitting red, green, and blue light? For red and near-infrared LEDs, performance is relatively robust, lasting tens of thousands of hours or even longer. Green LEDs perform slightly worse but can still endure over 10,000 hours. Unfortunately, blue LEDs fare the worst, with lifespans often limited to just a few hours—practically unusable under real-world conditions. Moreover, measurements of LED lifespan vary widely across different studies, largely because there’s no standardized testing protocol. Some researchers set the initial brightness higher, while others opt for lower levels. Additionally, test conditions differ dramatically, adding complexity and uncertainty to the research process. To address these challenges, some scientists have turned to accelerated lifetime testing, which involves subjecting LEDs to high-intensity conditions and then extrapolating the results back to normal operating brightness levels. Beyond brightness, researchers also closely monitor changes in voltage and the emission spectrum during testing, as these factors provide critical insights into why devices fail. There are several practical tips for conducting these tests: First, always start with the highest possible initial brightness setting, since the LED may initially spike before stabilizing. It’s also wise to measure multiple points at varying brightness levels for more accurate comparisons. Finally, proper encapsulation is essential—without it, external environmental factors like humidity and temperature can severely skew test results. But what exactly causes perovskite LEDs to be so short-lived? Broadly speaking, the issue stems from both internal and external factors. Internally, there are four primary concerns. The first is the presence of defects within the thin film itself. Perovskite films aren’t perfect crystals; they often contain vacancies or excess atoms, creating traps for electrons and allowing ions to migrate unpredictably. These defects not only degrade luminescence but also accelerate device failure. What’s more, perovskite materials inherently contain far more defects than traditional semiconductors like silicon or gallium arsenide, making them prone to inherent "malfunctions." The second internal issue is ion migration. Ions within perovskite materials—especially halogen ions—are highly mobile, particularly under the influence of electric fields or heat. As these ions move around, they disrupt the material’s composition, leading to uneven color distribution and even irreversible damage. This problem is especially pronounced in thin-film LEDs, where ions can easily infiltrate adjacent layers or even reach the electrodes, causing permanent degradation. Even with effective encapsulation that shields the device from external factors, ion migration continues to undermine durability. The third internal factor is carrier imbalance. LEDs rely on the recombination of electrons and holes within the emissive layer to produce light. If there’s an excess of either carriers—too many electrons or too many holes—the surplus charge ends up wasting energy in unintended areas, generating heat and shortening the device’s lifespan. It’s akin to a game of passing a ball between two teams: if one side has too many players while the other is understaffed, the ball won’t circulate smoothly, and mistakes are likely to occur. Finally, Joule heating exacerbates the problem. Defects, ion migration, and carrier imbalances all hinder the efficient recombination of electrons and holes, ultimately converting excess energy into heat. Unfortunately, perovskite materials have poor thermal conductivity, causing heat to accumulate rather than dissipate. Studies have shown that operating temperatures can soar as high as 113°C, a level severe enough to trigger interlayer diffusion and electrode degradation, further accelerating device failure. Externally, water, oxygen, light exposure, and temperature pose significant threats. Among these, water and oxygen are the most detrimental, as they can penetrate through defects in the thin film, disrupting the crystal structure. Interestingly, trace amounts of moisture can sometimes be beneficial—for instance, controlled humidity during annealing can help achieve a more uniform film. Similarly, while oxygen can mitigate certain unwanted reactions, it also accelerates material decomposition, particularly in organic-inorganic hybrid perovskites, which are more sensitive to oxidation. Light exposure poses another challenge: continuous illumination can destabilize the crystal structure and weaken chemical bonds within the material. Temperature-related issues are equally critical. Organic-inorganic perovskites tend to undergo structural changes when exposed to heat, while even fully inorganic variants may suffer from grain growth at elevated temperatures, leading to reduced luminescence efficiency. With these key challenges identified, current research efforts are primarily focused on addressing them—from improving film quality to optimizing device design. Let’s start by examining ways to enhance the thin-film properties, as the quality of the film directly impacts overall device performance. After all, no matter how much you refine the rest of the LED structure, poor film quality will inevitably limit its potential. One effective strategy is to fine-tune the material composition. Perovskites typically follow a general formula of ABX₃, where A, B, and X represent specific elements occupying distinct positions in the crystal lattice. By carefully selecting and mixing these components, researchers can optimize crystal growth, boosting both luminous efficiency and longevity. For example, incorporating cesium, methylammonium, or formamidinium ions into the A-site lattice can significantly improve film quality and stability. One notable study introduced an additive called BMCl, combined with a small amount of MABr, resulting in a perovskite film that crystallizes spontaneously at room temperature without the need for annealing. Remarkably, this approach extended the device’s lifespan by a staggering 10 times compared to conventional methods, enabling stable operation for up to 24.8 hours at a brightness level of 100 cd/m². On the B-site, lead ions are traditionally dominant, but researchers are increasingly exploring alternatives like zinc or manganese ions. Zinc ions, for instance, have an ionic radius similar to lead, allowing them to seamlessly integrate into the crystal lattice without disrupting its structure. Moreover, zinc doping helps reduce defect density, resulting in a denser, more uniform film with enhanced moisture resistance. In fact, experiments incorporating up to 30% zinc ions have already yielded impressive red-light LEDs with outstanding performance. As for the X-site, halogen ions play a crucial role in determining the LED’s emission color. Iodine produces red light, while chlorine generates blue light. However, chlorine ions are notoriously unstable and prone to migration, which can compromise device performance. To circumvent this issue, researchers are now favoring bromine or pure iodine-based perovskites, avoiding mixed-halogen compositions altogether. Another promising approach involves the strategic use of additives. By introducing specific compounds into the precursor solution during film formation, researchers can minimize defect formation and improve overall film quality.For instance, there’s an additive called SFB10, whose sulfate groups can bind to lead ions on the perovskite surface, forming a protective layer that not only reduces defects but also inhibits ion migration. LEDs emitting red light using this additive have achieved a T50 lifetime of up to 1.3 years at a current density of 5 mA/cm²—an exceptionally impressive result. Another approach involves adding a substance called FPMATFA, which effectively addresses two types of defects simultaneously: it first binds to the dangling bonds of halides, and secondly coordinates with excess lead ions. As a result, the LED’s lifespan has been dramatically improved—from just 0.25 hours to as long as 14 hours, showcasing remarkable performance. Sometimes, researchers even combine two additives, such as PEG and PEABr. While PEG helps fill grain boundaries and minimize pinholes, PEABr works to shrink the crystal size. When used together, these additives synergistically reduce energy loss and enhance overall stability. Finally, yet another strategy focuses on controlling the crystallization process itself. Since the thin film grows atop the transport layer, the quality of the latter directly influences how the perovskite crystals form. For example, the commonly used PEDOT:PSS transport layer has a surface that isn’t very hydrophilic, making it difficult for the perovskite solution to spread evenly—and often leading to chemical reactions that introduce defects. Later, some researchers experimented with alternative materials, like NiO, to address these challenges. ₓ When used as a transport layer, perovskites grow more uniformly on top of it, with significantly fewer defects—resulting in a lifetime that’s improved by more than 10 times compared to using PEDOT:PSS. Additionally, during fabrication, it’s common practice to apply an anti-solvent treatment: after depositing the film, another solvent is carefully coated onto the surface to wash away excess halogens, promoting better crystal growth. For instance, chloroform can be used to remove excess iodide ions, while a subsequent PMMA blocking layer effectively minimizes efficiency degradation. Some researchers even use dimethyl carbonate as the anti-solvent, which helps precisely control grain size and reduces energy losses. Now, let’s talk about optimizing device architecture. Once the thin film is ready, the device design becomes equally critical. The first key aspect is balancing charge carrier injection. Simply put, this means ensuring that electrons and holes meet precisely within the emissive layer. A common approach involves tuning the energy level structure of the transport layers, making it easier for both electrons and holes to enter the active region. For example, one study introduced a stepped-hole-transport-layer design, where each layer gradually lowers its energy levels. This arrangement enhances hole-injection efficiency, boosting brightness while simultaneously alleviating efficiency drops. Others have also added an intermediate layer between the transport and emissive layers. One such material, known as SO-DMAc, not only binds tightly to lead ions on the perovskite surface but also facilitates smoother electron transfer, thereby reducing the difficulty of hole injection. Devices incorporating this material achieve impressive performance at a wavelength of 682 nm, delivering a luminous efficiency of up to 21.8% and maintaining T50 (the time when half of the initial brightness remains) for 35 hours. Another strategy focuses on inhibiting ion migration. Since halogen ions tend to move erratically, the goal is to physically block their pathways. Researchers have addressed this issue by introducing rubidium and cesium ions into the perovskite lattice. Cesium ions integrate seamlessly into the crystal structure, effectively pinning down migrating halogen ions, while rubidium ions accumulate at grain boundaries and on the surface, further impeding ion movement. Combining these two approaches yields remarkable results: under a current density of 10 mA/cm², the device maintains T50 for over 60 hours—nearly matching the stability of OLEDs. Lastly, some scientists have explored replacing lead ions with transition metal ions like nickel or manganese. These metals’ 3d orbitals form strong chemical bonds with surrounding ligands, significantly increasing the energy barrier for halogen ion migration and thus limiting their erratic behavior. Moreover, adding specific organic ligands—such as the IMI ligand—can enhance this effect even further. The IMI ligand not only binds tightly to halogen ions, completely preventing their migration, but also promotes more orderly crystal alignment, leading to superior device performance.

The third is thermal management. If heat can’t dissipate effectively, device failure will inevitably occur more quickly. Currently, there are two main approaches: First, using substrates with excellent thermal conductivity, such as sapphire, which has a much higher thermal conductivity than glass. Under the same voltage conditions, devices mounted on sapphire substrates can maintain significantly lower surface temperatures and enjoy longer lifespans. Alternatively, some researchers are exploring single-crystal silicon substrates, which not only enhance heat dissipation but also help alleviate efficiency degradation. The second approach focuses on reducing heat generation itself—by optimizing device structures to improve light utilization and minimize energy conversion into heat. For instance, one innovative design features a specialized light-coupling structure that efficiently guides more light out of the device, thereby decreasing photon reabsorption and ultimately lowering heat production. As a result, red LED devices operating at a brightness of 100 cd/m² have demonstrated an impressive T50 lifetime of up to 4,806.7 hours. Finally, there’s packaging, which plays a crucial role in protecting LEDs from environmental threats like water and oxygen—two major culprits behind device degradation. Today, two primary packaging methods are commonly employed: One involves encapsulating the device within a hermetic shell made of a substrate and adhesive materials, often complemented by desiccants and deoxygenation agents inside. While this method offers superior barrier properties, it tends to compromise thermal performance. The other approach uses thin-film encapsulation, directly coating the device surface with materials like aluminum oxide or PDMS. This technique not only provides outstanding thermal conductivity but also enables the fabrication of flexible devices, making it particularly appealing for next-generation applications. Among these, PDMS-based encapsulation stands out for its ease of implementation and remarkable effectiveness in blocking moisture and oxygen, positioning it as a technology with significant growth potential. Looking ahead, the research trajectory for perovskite LEDs is already quite clear: the key priorities remain enhancing film quality, refining device architectures, and optimizing thermal management—all of which are intricately interconnected. For example, fewer defects in the film lead to reduced heat generation and lower thermal management challenges; meanwhile, improved carrier balance translates into higher efficiency, further minimizing heat output. Beyond these core areas, several emerging directions warrant attention. First, developing safer solvents is essential, as current ones can be toxic and significantly hinder the crystallization process. A new solvent that addresses these issues could simultaneously boost stability and reduce environmental impact. Second, advancing solvent-free film-forming technologies, such as vacuum evaporation, holds great promise. This method sidesteps many of the drawbacks associated with solution-based techniques—like uneven surfaces and numerous defects—while also allowing seamless integration with existing OLED production lines, thus driving down costs. Lastly, creating core-shell structured nanocrystals, where an outer layer of protective material encases the core, could mitigate unwanted side reactions, optimize charge injection, and effectively suppress ion migration, leading to more stable and reliable devices. In summary, perovskite LEDs have already overcome many critical hurdles, notably achieving substantial improvements in the lifetimes of red and green variants. The remaining challenge lies in mastering blue-light performance. Yet, if stability can be further enhanced, perovskite LEDs are poised to revolutionize the display and lighting industries by offering a cost-effective, high-efficiency alternative. Who knows? Perhaps the screens and lights we use in the future will all be powered by this groundbreaking technology.