Abstract:Enhancing device lifetime is one of the essential challenges in perovskite solar cells. The ultrathin Eu‐MOF layer is introduced at the interface between the electron‐transport layer and the perovskite absorber to improve the device stability. Both Eu ions and organic ligands in the MOF can reduce the defect concentration and improve carrier transport. Moreover, due to the Förster resonance energy transfer effect, Eu‐MOF in perovskite films can improve light utilization and reduce the decomposition under ultra… Show more
“…Meanwhile, Eu‐MOF also converts tensile strain to compressive strain in the perovskite films. [ 174 ] Table 5 summarizes the reported research work about 2D interface layer in PSCs so far. These 2D materials mainly regulate the electrical properties and the formation of perovskite films.…”
Q limit but the opencircuit voltage (V oc ) and fill factor (FF) are still far below the theoretical values. As we know, both V oc and FF relate to charge carrier dynamics including extraction and transport. Therefore, carrier managements including reducing non-radiative carrier recombination (bulk and interface), series or shunt resistance, and improving carrier extraction and transport are critical to further enhance the power conversion efficiency (PCE) of PSCs. In addition to high efficiency, the stability issues in perovskite must be solved before commercialization.From the standpoint of architecture of PSCs, the PSCs are essentially a heterojunction device with a multilayer construction, which consists of perovskite light absorption layer, carrier transport layer (CTL), and electrodes. [25,30] As a result, the rational design and modification of heterojunction interfaces have become key strategies to harness the full potential of PSCs. [31][32][33][34][35] A lack of in-depth understanding of the heterojunction interfaces and appropriate interface designs, specifically the buried interfaces under polycrystalline perovskite films, is impeding further advancements in perovskite photovoltaic performance and stability. [36][37][38][39][40][41][42] To date, many researches mainly focus on the top surfaces of perovskite. [43][44][45][46][47] However, due to the accumulation of deep-level trap states, it is known that unfavorable non-radiative recombination losses that impede device power outputs exist at the interfaces with bottom contact layers. [41,48] Consequently, it is urgently needed to compromise between these detrimental effects and beneficial effects.However, investigating these issues is more difficult compared with that on the top surfaces of perovskite. There are two kinds of techniques to study the buried interface, which are the in-situ and ex-situ methods. For in-situ method, the sum frequency generation (SFG) vibrational spectroscopy which is a nonlinear interface sensitive spectroscopy is applied to study/ analyze the molecular structure information at the buried interface. [49,50] In addition, the photoluminescence spectroscopy (PL) excited from the glass side can characterize carrier dynamics behavior of buried interface. [51] For ex-situ strategy, the buried interface will expose with a peeling-off method. Then the common characterization methods can be used to analyze exposed the buried surface of perovskite layer, such as PL, scanning electron microscope (SEM), atomic force microscopy (AFM), and Fourier transform infrared spectroscopy (FTIR). [52,53] It is still challenging to find ways to access the buried interfaces to achieve device efficiency limits. [54] Organic-inorganic hybrid perovskite solar cells (PSCs) are promising thirdgeneration solar cells. They exhibit high power conversion efficiency (PCE) and, in theory, can be manufactured with less energy than several more established photovoltaic technologies, particularly solution-processed PSCs. Various materials have been widely utiliz...
“…Meanwhile, Eu‐MOF also converts tensile strain to compressive strain in the perovskite films. [ 174 ] Table 5 summarizes the reported research work about 2D interface layer in PSCs so far. These 2D materials mainly regulate the electrical properties and the formation of perovskite films.…”
Q limit but the opencircuit voltage (V oc ) and fill factor (FF) are still far below the theoretical values. As we know, both V oc and FF relate to charge carrier dynamics including extraction and transport. Therefore, carrier managements including reducing non-radiative carrier recombination (bulk and interface), series or shunt resistance, and improving carrier extraction and transport are critical to further enhance the power conversion efficiency (PCE) of PSCs. In addition to high efficiency, the stability issues in perovskite must be solved before commercialization.From the standpoint of architecture of PSCs, the PSCs are essentially a heterojunction device with a multilayer construction, which consists of perovskite light absorption layer, carrier transport layer (CTL), and electrodes. [25,30] As a result, the rational design and modification of heterojunction interfaces have become key strategies to harness the full potential of PSCs. [31][32][33][34][35] A lack of in-depth understanding of the heterojunction interfaces and appropriate interface designs, specifically the buried interfaces under polycrystalline perovskite films, is impeding further advancements in perovskite photovoltaic performance and stability. [36][37][38][39][40][41][42] To date, many researches mainly focus on the top surfaces of perovskite. [43][44][45][46][47] However, due to the accumulation of deep-level trap states, it is known that unfavorable non-radiative recombination losses that impede device power outputs exist at the interfaces with bottom contact layers. [41,48] Consequently, it is urgently needed to compromise between these detrimental effects and beneficial effects.However, investigating these issues is more difficult compared with that on the top surfaces of perovskite. There are two kinds of techniques to study the buried interface, which are the in-situ and ex-situ methods. For in-situ method, the sum frequency generation (SFG) vibrational spectroscopy which is a nonlinear interface sensitive spectroscopy is applied to study/ analyze the molecular structure information at the buried interface. [49,50] In addition, the photoluminescence spectroscopy (PL) excited from the glass side can characterize carrier dynamics behavior of buried interface. [51] For ex-situ strategy, the buried interface will expose with a peeling-off method. Then the common characterization methods can be used to analyze exposed the buried surface of perovskite layer, such as PL, scanning electron microscope (SEM), atomic force microscopy (AFM), and Fourier transform infrared spectroscopy (FTIR). [52,53] It is still challenging to find ways to access the buried interfaces to achieve device efficiency limits. [54] Organic-inorganic hybrid perovskite solar cells (PSCs) are promising thirdgeneration solar cells. They exhibit high power conversion efficiency (PCE) and, in theory, can be manufactured with less energy than several more established photovoltaic technologies, particularly solution-processed PSCs. Various materials have been widely utiliz...
“…[15] To improve thermal stability and photothermal stability of PSCs, numerous effective methods have been demonstrated. [16] Among them, the most popular strategy is to make high quality perovskite absorber with effective passivation, [17][18][19][20][21][22] which enhances their resistance to thermal stress and irradiation. Meanwhile, thermostable charge transport layers and electrodes are also extensively studied to improve the thermal and photothermal stability of PSCs.…”
Special attention should be devoted to the thermal stability of hybrid perovskite solar cells (PSCs), because they are often operated at elevated temperatures. However, effective strategies are lacking for manipulation of heat flow in PSCs to improve their thermal stability. Here, a holistic solution is reported for the rapid removal of dissipated heat within the absorber by introducing hexagonal boron nitride (h‐BN) inside and radiator fin outside of the device. This strategy significantly improves the thermal conductivity of perovskite and speeds up the heat transfer of device, which effectively reduces the cell temperature under illumination of simulated AM 1.5G standard spectrum by ≈6.5 °C. Regardless of device configurations, the corresponding PSCs exhibit prolonged lifetimes aged at different temperatures, continuously operated under white light‐emitting diode (LED) lamp or full‐spectrum illumination. Of particular note, the optimized h‐BN/Cu device with n–i–p structure keeps 88% and 93% of its initial PCE after 1776 h of 85 °C thermal aging and 2451 h of maximum power point (MPP) tracking, respectively, and the device with p–i–n structure maintains 96% and 92% of its original PCE after 1704 h of 85 °C thermal aging and 2164 h of MPP tracking.
“…The Eu-MOF layer has multiple effects on the device properties, including improving the light absorption, changing the residual tensile strain into compressive strain and passivating the deep defect states. Through the synergistic impact induced by Eu-MOF, a highest PCE of 22.16% and long-term stability over 2000 h were achieved [ 60 ]. Figure 5 ( a ) Energy-level diagram for the device of FTO/La 3+ -doped TiO 2 /mp-TiO 2 /CH 3 NH 3 PbI 3 /Spiro-OMeTAD/Au (Reprinted/adapted with permission from Ref.…”
Section: Applications Of Ln
3+
In Perovskite Solar...mentioning
In recent years, rare-earth metals with triply oxidized state, lanthanide ions (Ln3+), have been demonstrated as dopants, which can efficiently improve the optical and electronic properties of metal halide perovskite materials. On the one hand, doping Ln3+ ions can convert near-infrared/ultraviolet light into visible light through the process of up-/down-conversion and then the absorption efficiency of solar spectrum by perovskite solar cells can be significantly increased, leading to high device power conversion efficiency. On the other hand, multi-color light emissions and white light emissions originated from perovskite nanocrystals can be realized via inserting Ln3+ ions into the perovskite crystal lattice, which functioned as quantum cutting. In addition, doping or co-doping Ln3+ ions in perovskite films or devices can effectively facilitate perovskite film growth, tailor the energy band alignment and passivate the defect states, resulting in improved charge carrier transport efficiency or reduced nonradiative recombination. Finally, Ln3+ ions have also been used in the fields of photodetectors and luminescent solar concentrators. These indicate the huge potential of rare-earth metals in improving the perovskite optoelectronic device performances.
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