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1.
    
The performance of perovskite solar cells is greatly affected by the crystallization of the perovskite active layer. Perovskite crystal grains should neatly arrange and penetrate the entire active layer for an ideal perovskite crystallization. These kinds of crystallized perovskite films exhibit fewer defects and longer carrier lifetime, which is beneficial to enhance the performance of perovskite solar cells. Here, by testing the residual charge of perovskite solar cells with different crystallization conditions, it is demonstrated that the residual charge exists widely at the grain boundary, which is parallel to the device, and the residual charge is related to the performance of the perovskite solar cells. Single crystal grains neatly arranged and penetrate the entire active layer can generate less residual charge and improve device performance of the perovskite solar cells. The results also show that the long decay time of open-circuit voltage comes from the detrapping of trapped carriers. The residual charge testing technology provides a new idea for the investigation of carrier trap and detrap characteristics in photovoltaic devices.  相似文献   

2.
    
The origin of performance enhancements in p‐i‐n perovskite solar cells (PSCs) when incorporating low concentrations of the bulky cation 1‐naphthylmethylamine (NMA) are discussed. A 0.25 vol % addition of NMA increases the open circuit voltage (Voc) of methylammonium lead iodide (MAPbI3) PSCs from 1.06 to 1.16 V and their power conversion efficiency (PCE) from 18.7% to 20.1%. X‐ray photoelectron spectroscopy and low energy ion scattering data show NMA is located at grain surfaces, not the bulk. Scanning electron microscopy shows combining NMA addition with solvent assisted annealing creates large grains that span the active layer. Steady state and transient photoluminescence data show NMA suppresses non‐radiative recombination resulting from charge trapping, consistent with passivation of grain surfaces. Increasing the NMA concentration reduces device short‐circuit current density and PCE, also suppressing photoluminescence quenching at charge transport layers. Both Voc and PCE enhancements are observed when bulky cations (phenyl(ethyl/methyl)ammonium) are incorporated, but not smaller cations (Cs/MA)—indicating size is a key parameter. Finally, it demonstrates that NMA also enhances mixed iodide/bromide wide bandgap PSCs (Voc of 1.22 V with a 1.68 eV bandgap). The results demonstrate a facile approach to maximizing Voc and provide insights into morphological control and charge carrier dynamics induced by bulky cations in PSCs.  相似文献   

3.
    
Despite the outstanding power conversion efficiency (PCE) of perovskite solar cells (PSCs) achieved over the years, unsatisfactory stability and lead toxicity remain obstacles that limit their competitiveness and large-scale practical deployment. In this study, in situ polymerizing internal encapsulation (IPIE) is developed as a holistic approach to overcome these challenges. The uniform polymer internal package layer constructed by thermally triggered cross-linkable monomers not only solidifies the ionic perovskite crystalline by strong electron-withdrawing/donating chemical sites, but also acts as a water penetration and ion migration barrier to prolong shelf life under harsh environments. The optimized MAPbI3 and FAPbI3 devices with IPIE treatment yield impressive efficiencies of 22.29% and 24.12%, respectively, accompanied by remarkably enhanced environmental and mechanical stabilities. In addition, toxic water-soluble lead leakage is minimized by the synergetic effect of the physical encapsulation wall and chemical chelation conferred by the IPIE. Hence, this strategy provides a feasible route for preparing efficient, stable, and eco-friendly PSCs.  相似文献   

4.
    
Organic-inorganic lead halide perovskite are promising photovoltaic materials, but their intrinsic defects and crystalline quality severely deteriorate the solar cells efficiency and stability. Herein, potassium 1,1,2,2,3,3-hexafluoroprop-ane-1,3-disulfonimide (KHFDF) is introduced into PbI2 precursor solution to passivate various defects and improve the crystalline quality of perovskite films. It is found that KHFDF can inhibit PbI2 crystallization, thus tuning the crystal orientation and growth of perovskite films. Furthermore, KHFDF with dual-functional sulfonyl group cannot only passivate grain boundaries (GBs), but also passivate the defects at GBs via strong interaction with undercoordinated Pb2+ and/or hydrogen bonding with FA+, while the K+ counter cations allow ionic interaction with undercoordinated I−. As a result, the KHFDF-modified films exhibit high quality with a larger grain size and a reduced trap-state density, thereby suppressing the trap-state nonradiative recombination. And the devices show a champion efficiency up to 24.15%, benefiting from a sharp enhancement of open-circuit voltage (Voc) of 1.183 V and fill factor of 81.78%. In addition, due to the enhanced humidity tolerance and chemical structure stability, the devices exhibit excellent long-term humidity and thermal stability without encapsulation.  相似文献   

5.
    
The organic–inorganic halide CH3NH3PbI3 (MAPbI3) has been the most commonly used light absorber layer of perovskite solar cells (PSCs); however, solution‐processed MAPbI3 films usually suffer from random crystal orientation and high trap density, resulting in inferior power conversion efficiency (PCE) with open circuit voltage (Voc) being typically below 1.2 V for PSC devices. Herein, for the first time an imidazole sulfonate zwitterion, 4‐(1H‐imidazol‐3‐ium‐3‐yl)butane‐1‐sulfonate (IMS), is applied as a bifunctional additive in regular‐structure planar heterojunction PSC devices to regulate the crystal orientation, yielding highly ordered MAPbI3 film and passivating the trap states of the film. Such a dual effect of IMS is fulfilled via coordination interactions between the sulfonate moiety of IMS with the Pb2+ ion and the electrostatic interaction between the imidazole of IMS with the I– ion of MAPbI3. As a result, under a optimized IMS doping ratio of 0.5 wt%, the PSC device exhibits a significant increase in PCE from 18.77% to 20.84%, with suppressed current–voltage hysteresis and promoted ambient stability. Moreover, a high Voc of 1.208 V is achieved under a higher IMS doping ratio of 1.2 wt%, which is the highest Voc for regular‐structure MAPbI3 planar PSC devices based on TiO2 electron transport layer.  相似文献   

6.
A key issue for perovskite solar cells is the stability of perovskite materials due to moisture effects under ambient conditions, although their efficiency is improved constantly. Herein, an improved CH3NH3PbI3?xClx perovskite quality is demonstrated with good crystallization and stability by using water as an additive during crystal perovskite growth. Incorporating suitable water additives in N,N‐dimethylformamide (DMF) leads to controllable growth of perovskites due to the lower boiling point and the higher vapor pressure of water compared with DMF. In addition, CH3NH3PbI3?xClx · nH2O hydrated perovskites, which can be resistant to the corrosion by water molecules to some extent, are assumed to be generated during the annealing process. Accordingly, water additive based perovskite solar cells present a high power conversion efficiency of 16.06% and improved cell stability under ambient conditions compared with the references. The findings in this work provide a route to control the growth of crystal perovskites and a clue to improve the stability of organic–inorganic halide perovskites.  相似文献   

7.
    
The solution processing in hybrid perovskite films inevitably results in the formation of detrimental defects at grain boundaries (GBs) that deteriorate the optoelectronic properties and bring about severe hysteresis as well as operational instability. Here, an effective scenario to alleviate the imperfection issue at perovskite GBs via incorporating pyridinic nitrogen-doped graphdiyne (N-GDY) is proposed. Taking full advantage of periodic acetylenic linkages and introduced pyridinic N atoms, the deep-level trap states like Pb–I antisite defects and under-coordinated Pb atoms are considerably passivated, thus diminishing the undesired non-radiative recombination. Additionally, the spatial confinement coupling with electrostatic repulsion effect originated from the intrinsic 2D structure of N-GDY, has been identified to deal with the halide ion migration behavior. Such contributions are further theoretically evidenced with the charge density delocalization as well as the ion migration energy barrier elevation. The authors unprecedentedly verified the superiorities based on the flexible chemical-tailorability of atomic crystal GDY materials toward polycrystalline perovskite related energy conversion devices.  相似文献   

8.
    
Hybrid organic/inorganic perovskite solar cells (PSCs) have shown great potential in meeting the future challenges in energy and environment. Solvent‐vapor‐assisted posttreatment strategies are developed to improve the perovskite film quality for achieving higher efficiency. However, the intrinsic working mechanisms of these strategies have not been well understood yet. This study identifies an MA2Pb3I8(DMSO)2 intermediate phase formed during the annealing process of methylammonium lead triiodide in dimethyl sulfoxide (DMSO) atmosphere and located the reaction sites at perovskite grain boundaries by observing and rationalizing the growth of nanorods of the intermediate. This enables us to propose and validate an intermediate‐assisted grain‐coarsening model, which highlights the activation energy reduction for grain boundary migration. Leveraging this mechanism, this study uses MABr/DMSO mixed vapor to further enhance grain boundary migration kinetics and successfully obtain even larger grains, leading to an impressive improvement in power conversion efficiency (17.64%) relative to the pristine PSCs (15.13%). The revelation of grain boundary migration‐assisted grain growth provides a guide for the future development of polycrystalline perovskite thin‐film solar cells.  相似文献   

9.
    
The lateral device structure for perovskite solar cells (PSCs) has garnered significant attention, primarily due to its elimination of the need for expensive transparent electrodes. However, the performance of lateral devices, which are more sensitive to crystal quality and charge carrier transport bottlenecks, has lagged far behind the predominant vertical PSCs. Herein, by modulating the crystal nucleation and growth processes of thin FA0.75MA0.25PbI3 (FA = formamidinium; and MA = methylammonium) single crystals, crystal quality and carrier transport are improved, resulting in a power conversion efficiency (PCE) of 12.64%, a record for lateral PSCs. Investigation of the device's stability reveals that iodide ion migration is suppressed due to a reduction in the iodide vacancy concentration combined with weak interface iodide ion migration. It is shown that the latter effect is a result of the perpendicular direction of the ion migration and the electric field in the lateral PSCs. Consequently, these lateral single-crystal PSCs display remarkable operational stability, retaining 100% of their initial PCE after 1200 h of steady-state output at the maximum power point voltage (Vmpp) under 1 sun illumination. This work highlights the advantages of lateral single-crystal devices and their potential to address key ion migration issues of PSCs.  相似文献   

10.
    
Organic–inorganic lead halide perovskites have shown great future for application in solar cells owing to their exceptional optical and electronic properties. To achieve high‐performance perovskite solar cells, a perovskite light absorbing layer with large grains is desirable in order to minimize grain boundaries and recombination during the operation of the device. Herein, a simple yet efficient approach is developed to synthesize perovskite films consisting of monolithic‐like grains with micrometer size through in situ deposition of octadecylamine functionalized single‐walled carbon nanotubes (ODA‐SWCNTs) onto the surface of the perovskite layer. The ODA‐SWCNTs form a capping layer that controls the evaporation rate of organic solvents in the perovskite film during the postthermal treatment. This favorable morphology in turn dramatically enhances the short‐circuit current density of the perovskite solar cells and almost completely eliminates the hysteresis. A maximum power conversion efficiency of 16.1% is achieved with an ODA‐SWCNT incorporated planar solar cell using (FA0.83MA0.17)0.95Cs0.05Pb(I0.83Br0.17)3 as light absorber. Furthermore, the perovskite solar cells with ODA‐SWCNT demonstrate extraordinary stability with performance retention of 80% after 45 d stability testing under high humidity (60–90%) environment. This work opens up a new avenue for morphology manipulation of perovskite films and enhances the device stability using carbon material.  相似文献   

11.
    
Cs/FA/MA triple cation perovskite films have been well developed in the antisolvent dripping method, attributable to its outstanding photovoltaic and stability performances. However, a facile and effective strategy is still lacking for fabricating high‐quality large‐grain triple cation perovskite films via sequential deposition method a, which is one of the key technologies for high efficiency perovskite solar cells. To address this issue, a δ‐CsPbI3 intermediate phase growth (CsPbI3‐IPG) assisted sequential deposition method is demonstrated for the first time. The approach not only achieves incorporation of controllable cesium into (FAPbI3)1–x(MAPbBr3)x perovskite, but also enlarges the perovskite grains, manipulates the crystallization, modulates the bandgap, and improves the stability of final perovskite films. The photovoltaic performances of the devices based on these Cs/FA/MA perovskite films with various amounts of the δ‐CsPbI3 intermediate phase are investigated systematically. Benefiting from moderate cesium incorporation and intermediate phase‐assisted grain growth, the optimized Cs/FA/MA perovskite solar cells exhibit a significantly improved power conversion efficiency and operational stability of unencapsulated devices. This facile strategy provides new insights into the compositional engineering of triple or quadruple cation perovskite materials with enlarged grains and superior stability via a sequential deposition method.  相似文献   

12.
    
Interfacial loss arising from defect trapping, contact barrier, and energy level alignment in the emerged perovskite solar cells (PSCs), is one of the most important issues to address for both improved photoconversion efficiency and long-term operational stability. The recent endeavors on the interfacial embedding of nanocrystals (NCs) in desired locations of PSCs have shown great success in terms of eliminating the interfacial loss in PSCs, while there is a lack of review to summarize the advances of NCs embedding for improved carrier dynamics and inhibited environmental degradation. Present study systematically analyzes the recent achievements on the embedding of a series of NCs including carbon dots, perovskite NCs, II-VI semiconductor NCs, metal/alloy NCs, which are intentionally introduced in desired layers/interfaces of PSCs. The specific functionality of the NCs embedding including carrier dynamic modulation, crystallinity enhancement, defect passivation, light trapping, and stability enhancement are sorted out, according to the requirement of each layer in PSCs. Finally, the current challenges and future perspectives of NCs embedding for perovskite-based optoelectronic devices is outlook. The present study provides a guide for developing NCs-based additives for high-performance PSCs is believed.  相似文献   

13.
    
The fast developing perovskite solar cells shows high efficiency and low cost. However, the stability problem restricts perovskite from commercial use. In this work, we have studied the effect of grain orientation on the morphological stability of perovskite thin films. By tuning the inorganic/organic ratio in the precursor solution, perovskite thin films with both high crystallinity and good morphological stability have been fabricated. The thermal stability of perovskite solar cells based on the optimized films has been tested. The device performance shows no degradation after annealing at 100℃ for 5 h in air. This finding provides general guidelines for the development of thermally stable perovskite solar cells.  相似文献   

14.
    
With a certified efficiency as high as 25.2%, perovskite has taken the crown as the highest efficiency thin film solar cell material. Unfortunately, serious instability issues must be resolved before perovskite solar cells (PSCs) are commercialized. Aided by theoretical calculation, an appropriate multifunctional molecule, 2,2-difluoropropanediamide (DFPDA), is selected to ameliorate all the instability issues. Specifically, the carbonyl groups in DFPDA form chemical bonds with Pb2+ and passivate under-coordinated Pb2+ defects. Consequently, the perovskite crystallization rate is reduced and high-quality films are produced with fewer defects. The amino groups not only bind with iodide to suppress ion migration but also increase the electron density on the carbonyl groups to further enhance their passivation effect. Furthermore, the fluorine groups in DFPDA form both an effective barrier on the perovskite to improve its moisture stability and a bridge between the perovskite and HTL for effective charge transport. In addition, they show an effective doping effect in the HTL to improve its carrier mobility. With the help of the combined effects of these groups in DFPDA, the PSCs with DFPDA additive achieve a champion efficiency of 22.21% and a substantially improved stability against moisture, heat, and light.  相似文献   

15.
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16.
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Here we demonstrate a room-temperature drop-coating method for MAPbI3 films. By using low-boiling-point solvent, high-quality MAPbI3 films were made by simply casting a drop of solution onto the substrate at room temperature. This approach took advantage of the synergistic effect of good wettability and volatility of the solvent, enabling high nuclei density and compact film at room temperature. The crystal growth in different solvents was in-situ observed by using optical microscope, which helped us to understand the mechanism for the formation of different film morphology. Perovskite solar cells gave a PCE of 18.21%.  相似文献   

17.
    
All-inorganic perovskite cesium lead iodide (CsPbI3) exhibits excellent prospects for commercial application as a light absorber in single-junction or tandem solar cells due to its outstanding thermal stability and proper bandgap. However, the device performance of CsPbI3-based perovskite solar cells (PSCs) is still restricted by the unsatisfactory crystal quality and severe non-radiative recombination. Herein, inorganic additive ammonium halides are introduced into the precursor solution to regulate the nucleation and crystallization of the CsPbI3 film by exploiting the atomic interaction between the ammonium group and the Pb–I framework. The grain boundaries and interfacial contact of the CsPbI3 film have been improved, which leads to significant suppression in the non-radiative recombination and an enhancement in the charge transport ability. With these benefits, a high efficiency of 18.7% together with an extraordinarily high fill factor of 0.83–0.84 has been achieved, comparable to the highest records reported so far. Moreover, the cell exhibits ultra-high photoelectrical stability under continuous light illumination and high bias voltage with 96% of its initial power-conversion efficiency being sustained after 2000 h operation, even superior to the world-champion CsPbI3 solar cell. The findings are promising for the development and application of all-inorganic PSCs using a simple inorganic additive strategy.  相似文献   

18.
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Here we demonstrate a room-temperature drop-coating method for MAPbl3 films.By using low-boiling-point solvent,high-quality MAPbl3 films were made by simply casting a drop of solution onto the substrate at room temperature.This approach took advantage of the synergistic effect of good wettability and volatility of the solvent,enabling high nuclei density and compact film at room temperature.The crystal growth in different solvents was in-situ observed by using optical microscope,which helped us to understand the mechanism for the formation of different film morphology.Perovskite solar cells gave a PCE of 18.21％.  相似文献   

19.
    
Well-engineered buried interfaces play a pivotal role in achieving high-performance perovskite solar cells (PSCs). A superior buried interface involves controlled perovskite crystallization, efficient charge transfer across interfaces, and robust interfacial bonding. Here, a class of innovative additives, benzoyl sulfonyl molecules including 4-sulfobenzoic acid monopotassium salt (K-SBA), and 4-sulfamoylbenzoic acid (SBA) is introduced to tailer the SnO2/perovskite buried interface, aiming to meet these essential criteria. Among them, K-SBA performed better. The findings reveal that the functional groups of K-SBA establish interactions with both SnO2 and perovskite, leading to effective bilateral passivation and mitigation of interface stress. This results in the formation of a pore-free buried interface and high-quality perovskite films with substantial crystal sizes. Consequently, PSCs incorporating K-SBA exhibited a notable increase in efficiency, achieving 24.56% efficiency compared to the control device's 22.27%. Furthermore, these K-SBA-enhanced PSCs maintain 90% of their original efficiency even after 500 h of maximum power point tracking. This work provides valuable insights for further refinement and advancement of buried interfaces in PSCs.  相似文献   

20.
    
Organometal halide perovskite solar cells (PeSCs) are regarded as promising photovoltaics due to their outstanding power conversion efficiencies (PCEs). However, even though their PCEs are achieved over 20%, their intrinsically poor stability is a big bottleneck for their practical uses. Here, a simple method is reported using phenyl‐C61‐butyric acid methyl ester as a molecular additive to improve thermal stability of organometal halide perovskite crystals, which also improves the PCEs of the associated PeSCs. Moreover, by varying the grain size of perovskite crystals up to ≈150 µm, it is demonstrated that grain boundary plays a significant role in their thermal stability. Cells with smaller grain interface area (i.e., larger grain size) have higher thermal stability. The additive is located at grain boundaries and found to induce electron transfer reactions with halogens in the perovskite. The reaction products chemically passivate perovskite crystals and strongly bind halogen atoms at grain boundaries to their crystal lattice, preventing them from exiting from the crystal lattice, which improves thermal stability of perovskite crystals. This study offers a simple method for improving thermal stability of perovskite without any loss and opens up the possibility of the use of various molecular additives to achieve highly stable PeSCs.  相似文献   

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