Inorganic CsPbI2Br Perovskite Research Articles

Efficient carbon-based CsPbI2Br perovskite solar cells using bifunctional polymer modification

The inorganic CsPbI2Br perovskite with excellent thermal stability has become one of the potential candidates for commercial perovskite solar cells (PSC) in the future.

Highly electroluminescent and stable inorganic CsPbI2Br perovskite solar cell enabled by balanced charge transfer

• Pre-treated SnO 2 has a multifunctional effect on the crystallization of CsPbI 2 Br film. • 5-AVABr post-treatment can effectively passivate CsPbI 2 Br film surface defects. • High-performance CsPbI 2 Br PBDs are prepared by bifacial modification method. Compared to the hybrid perovskite, inorganic perovskite has potential to improve the thermal stability, but the photoelectric performance is limited by the film defect and unbalanced charge transfer. In this work, we pre-treat SnO 2 layer with fullerene-ethylenediamine derivatives (C 60 -EDA and C 70 -EDA) and post-treat the CsPbI 2 Br perovskite film using 5-aminovaleric acid hydrobromide (5-AVABr), leading to the high photovoltaic/electroluminescent (PV/EL) performance. Due to the improved film-forming property, SnO 2 :C 60 -EDA and SnO 2 :C 70 -EDA induced large-grain CsPbI 2 Br film with low defect density and superior interface connectivity. The combined pre-post treatments balance the charge transfer at N-I-P interface for injection and extraction, respectively, leading to the efficient inorganic perovskite bifunction device (PBD). The target CsPbI 2 Br device achieved a PV efficiency of 16.58% (stabilized to 16.30%) with a V oc of 1.32 ± 0.06 V in the PV mode and the EL external quantum efficiency (EQE EL ) of 6.2% in the EL mode, much higher than the control device (PV efficiency of 12.06% and EQE EL of 1.0%). Thus, we demonstrated the reciprocity relation between PV and EL modes that a great solar cell needs to be a great LED. Besides, the performance can still maintain 93% and 80% of its initial values when stored in dry air atmosphere for 65 days and heated at 85 °C for 12 days, respectively. The stable PBD has potential to utilize the solar energy more efficiently for smart power supply in the electronics.

Oxidization-Free Spiro-OMeTAD Hole-Transporting Layer for Efficient CsPbI2Br Perovskite Solar Cells.

The inorganic CsPbI2Br perovskite faces serious challenges of low phase stability and high moisture sensitivity. The moisture controllable process of a hole-transporting layer (HTL) is crucial for the development of stable and efficient inorganic perovskite solar cells (IPSCs). In this work, we proposed an oxidization-free spiro-OMeTAD hole-transport layer (HTL) with a preoxidized spiro-OMeTAD solution to prevent moisture and completely avoid the phase transition of CsPbI2Br from the α-phase to β-phase. The oxidization-free HTL exhibited improved surface hydrophobic properties, smoother morphology, and optimized energy-level alignment compared with a traditional HTL. As a result, the CsPbI2Br-based IPSCs achieved an efficiency of up to 14.2 and 86.6% of the initial power conversion efficiency (PCE) with 2000 h storage. Meanwhile, this oxidization-free HTL was applied in CH3NH3PbI3-based PSCs and obtained 13.8% PCE enhancement, which proved the universality of the solution preoxidization tactic. We believe that the oxidization-free HTL could be an efficient strategy to replace traditional HTLs and can be widely used in perovskite solar cells, especially in moisture-sensitive PSCs.

Defect passivation strategy for inorganic CsPbI2Br perovskite solar cell with a high-efficiency of 16.77%

All-inorganic halide perovskite solar cells (PSCs) have acquired great progress, especially CsPbI2Br. However, their photoelectric conversion efficiency (PCE) remains far below the theoretical predictions. Non-radiative recombination is one of the important issues affecting the photoelectric performance of the PSCs, and the defective lead ions derived from the evaporation of halide ions in the inorganic perovskite are the principal non-radiative recombination centers. Herein, the non-radiative recombination is effectively suppressed by introducing the N-methyl-2-pyrrolidone (NMP) as a Lewis base molecule to passivate the defective lead ions. Therefore, by adjusting the dosage of NMP, the smooth and pinhole-free CsPbI2Br perovskite film is obtained and the optimized device exhibits a champion PCE of 16.77% with an excellent fill factor (FF) of 0.80. This work proves the effectiveness of passivation using Lewis base molecules to prevent non-radiative recombination defects in inorganic perovskite.

Guanidinium Passivation for Air‐Stable Rubidium‐Incorporated Cs(1 − x)RbxPbI2Br Inorganic Perovskite Solar Cells

Inorganic CsPbI2Br perovskite has gained growing attention due to its potential for improving device performance and stability. However, the notorious phase transition from the photoactive to photoinctive phase in ambient atmosphere hinders its further development. Herein, air‐stable rubidium (Rb)‐incorporated Cs(1 − x)RbxPbI2Br perovskite with guanidinium bromide (GABr) post‐treatment is demonstrated. The incorporation of smaller monovalent Rb cation contributes to a contraction of the perovskite crystal, leading to an improvement in structure stability. In addition, GABr modification induces a 2D/3D heterostructure perovskite with high crystallinity, appropriate surface morphology, favorable electronic properties, and significantly reduced trap‐state density. Consequently, the fabricated perovskite solar cells deliver a power conversion efficiency (PCE) of 15.6%, which is much higher than the 12.9% reported for reference CsPbI2Br‐based devices. Meanwhile, the significantly enhanced long‐term (88% of initial PCE after 60 days), thermal (76% of initial PCE after 30 days) as well as light soaking (90% of initial PCE after 300 min) stability in ambient atmosphere is demonstrated.

A facile surface passivation method for efficient inorganic CsPbI2Br perovskite solar cells with efficiencies over 15%

Recently, perovskite solar cells (PVSCs) based on CsPbI2Br have attracted increasing attention owing to their good balance between efficiency and stability. Solution-processed CsPbI2Br perovskites usually contain various defects which need passivation for PVSCs with high-performance as well as good stability. Since the degradation of perovskite films usually begins at the grain boundaries, here we report a facile defect passivation strategy by spin-coating a KF solution on the CsPbI2Br perovskite surface. The deposited KF salt mostly locates at the grain boundaries of the perovskite surface, resulting in PVSCs with improved stability. Both steady-state and time-resolved photoluminescence results suggest that the defects of perovskite were significantly passivated by KF treatment. Consequently, the best-performance PVSC based on CsPbI2Br with KF treatment shows an enhanced power conversion efficiency (PCE) of 15.01% with a larger open circuit voltage (VOC) of 1.26 V in comparison with the pristine CsPbI2Br-based counterpart which exhibits an inferior PCE of 14.14% with a VOC of 1.18 V.

Acetate-Based Crystallization Kinetics Modulation of CsPbI2Br for Improved Photovoltaic Performance

Inorganic CsPbI2Br perovskite has emerged to be a promising candidate for photovoltaic materials, while developing additive engineering strategies to address the issues of defect induced crystallin...

Europium and Acetate Co-doping Strategy for Developing Stable and Efficient CsPbI2 Br Perovskite Solar Cells.

All-inorganic perovskite solar cells have developed rapidly in the last two years due to their excellent thermal and light stability. However, low efficiency and moisture instability limit their future commercial application. The mixed-halide inorganic CsPbI2 Br perovskite with a suitable bandgap offers a good balance between phase stability and light harvesting. However, high defect density and low carrier lifetime in CsPbI2 Br perovskites limit the open-circuit voltage (Voc < 1.2 V), short-circuit current density (Jsc < 15 mA cm-2 ), and fill factor (FF < 75%) of CsPbI2 Br perovskite solar cells, resulting in an efficiency below 14%. For the first time, a CsPbI2 Br perovskite is doped by Eu(Ac)3 to obtain a high-quality inorganic perovskite film with a low defect density and long carrier lifetime. A high efficiency of 15.25% (average efficiency of 14.88%), a respectable Voc of 1.25 V, a reasonable Jsc of 15.44 mA cm-2 , and a high FF of 79.00% are realized for CsPbI2 Br solar cells. Moreover, the CsPbI2 Br solar cells with Eu(Ac)3 doping demonstrate excellent air stability and maintain more than 80% of their initial power conversion efficiency (PCE) values after aging in air (relative humidity: 35-40%) for 30 days.

Large-Area Organic-Free Perovskite Solar Cells with High Thermal Stability.

Organic-free perovskite solar cells (PSCs) have been considered as the most promising candidate for achieving long-term stability. Here, we demonstrate an organic-free PSC consisting of inorganic CsPbI2Br perovskite, nickel oxide hole transport layer, and niobium oxide electron transport layer. A maximum power conversion efficiency (PCE) of 11.20% is achieved with an active area of 5 cm2, and it increases to 14.11% with smaller area. More importantly, the organic-free PSCs show excellent thermal stability with PCE remaining above 98% of its initial value when heated at 100 °C for 150 min. Postannealing at a proper temperature further increases its maximum PCE to 14.45%, which is the highest among any reported all-inorganic PSCs with a p-i-n structure. The enhanced performance of the postannealed device is ascribed to the decreased trap-state density and improved interface charge-transfer properties. These results demonstrated that this novel organic-free device architecture can be employed to fabricate efficient and stable PSCs for large-scale manufacturing.

Pb‐Reduced CsPb0.9Zn0.1I2Br Thin Films for Efficient Perovskite Solar Cells

AbstractFabrication of efficient Pb reduced inorganic CsPbI2Br perovskite solar cells (PSC) are an important part of environment‐friendly perovskite technology. In this work, 10% Pb reduction in CsPb0.9Zn0.1I2Br promotes the efficiency of PSCs to 13.6% (AM1.5, 1sun), much higher than the 11.8% of the pure CsPbI2Br solar cell. Zn2+ has stronger interaction with the anions to manipulate crystal growth, resulting in size‐enlarged crystallite with enhanced growth orientation. Moreover, the grain boundaries (GBs) are passivated by the Cs‐Zn‐I/Br compound. The high quality CsPb0.9Zn0.1I2Br greatly diminishes the GB trap states and facilitates the charge transport. Furthermore, the Zn4s‐I5p states slightly reduce the energy bandgap, accounting for the wider solar spectrum absorption. Both the crystalline morphology and energy state change benefit the device performance. This work highlights a nontoxic and stable Pb reduction method to achieve efficient inorganic PSCs.

Solution‐Processed 2D Nb2O5(001) Nanosheets for Inverted CsPbI2Br Perovskite Solar Cells: Interfacial and Diffusion Engineering

Herein, solution‐processed 2D Nb2O5(001) nanosheets (c‐Nb2O5 NS) are prepared and combined with [6,6]‐phenyl‐C61‐butyric acid methyl ester (PC61BM) as an electron transport layer (ETL) for inverted inorganic CsPbI2Br perovskite solar cells (PeSCs). The PeSCs with a c‐Nb2O5/PC61BM bilayer ETL yield a high power conversion efficiency (PCE) up to 11.74%, remarkably outperforming the devices with only PC61BM (9.10%) and those with the state‐of‐the‐art ZnO/C60 ETL (10.65%) prepared under the same conditions. More importantly, the nonencapsulated PeSCs with c‐Nb2O5 exhibit a high thermal stability with only 20% PCE loss after 400 h thermal aging at 85 °C. Such an impressive performance and a high stability can be attributed to the introduction of c‐Nb2O5(001) NS with favorable band levels, strong acid nature, and the small lattice fringe spacing along the large lateral (001) surface, which not only facilitate the electron transport, blocking the hole transport, but also contribute to defect passivation and retard the iodine ions diffusion toward the Ag electrode. This study thus provides a deeper insight for the interfacial design in inverted inorganic PeSCs and contributes to PCE improvement in the future.

In situ formation of a 2D/3D heterostructure for efficient and stable CsPbI2Br solar cells

A 2D/3D heterostructure was formed based on inorganic CsPbI2Br perovskite, contributing to a high efficiency device with enhanced stability.

Large-Area Organic-Free Perovskite Solar Cells with High Thermal Stability

Organic-free perovskite solar cells (PSCs) with all inorganic functional layers have been considered as the most promising candidate for achieving long-term stability. Here, we demonstrate the first organic-free PSC consisted of inorganic CsPbI2Br perovskite, nickel oxide hole transport layer, and niobium oxide electron transport layer. The as-fabricated organic-free PSC exhibits a maximum PCE of 11.20% with a large active area of 5 cm2. The PCE is increased to 14.11% with smaller area and retains above 98% of its initial value after being stored in nitrogen atmosphere for 30 days. More importantly, the organic-free PSCs show excellent thermal stability with PCE remained above 98% of its initial value after being heated at 100 °C for 150 min. The high thermal stability of the device makes it possible to conduct post-annealing to further increase its maximum PCE to 14.45%, which is the highest among any reported all-inorganic PSCs with p-i-n structure. The enhanced performance of the post-annealed device is ascribed to the decreased trap-state density and improved interface charge transfer properties of the device. These results demonstrated that this novel organic-free device architecture can be employed to fabricate efficient and stable PSCs for large-scale manufacturing.

Iodine-Optimized Interface for Inorganic CsPbI2Br Perovskite Solar Cell to Attain High Stabilized Efficiency Exceeding 14.

Recently, inorganic CsPbI2Br perovskite is attracting ever‐increasing attention for its outstanding optoelectronic properties and ambient phase stability. Here, an efficient CsPbI2Br perovskite solar cell (PSC) is developed by: 1) using a dimension‐grading heterojunction based on a quantum dots (QDs)/bulk film structure, and 2) post‐treatment of the CsPbI2Br QDs/film with organic iodine salt to form an ultrathin iodine‐ion–enriched perovskite layer on the top of the perovskite film. It is found that the above procedures generate proper band edge bending for improved carrier collection, resulting in effectively decreased recombination loss and improved hole extraction efficiency. Meanwhile, the organic capping layer from the iodine salt also surrounds the QDs and tunes the surface chemistry for further improved charge transport at the interface. As a result, the champion device achieves long‐term stabilized power conversion efficiency beyond 14%.

Temperature-assisted crystallization for inorganic CsPbI2Br perovskite solar cells to attain high stabilized efficiency 14.81%

Due to its super thermal stability, inorganic CsPbI2Br perovskite has attracted more and more attention in the field of photovoltaic application. However, its device performance, as reported to date, is greatly challenged in preparing CsPbI2Br films with both sufficient absorbance and high quality. Herein, crystallization engineering is applied in producing solution-processed CsPbI2Br film to guarantee sufficient light harvesting and effective carrier extraction. Further study proves that the precursor solution temperature would largely affect the crystallization progress: (1) the nucleation step is highly related to the solubility of precursor in a specific solvent or solvents at elevated temperatures; (2) the crystal growth rate is highly related to the solvent evaporation rate. To obtain thick film with larger crystalline grain size, the precursor solution temperature should be carefully adjusted for both suppressing the formation of too many nuclei and increasing the crystallization rate at the same time. Finally, the optimized CsPbI2Br would be obtained when the precursor solution is maintained at 100 °C, the corresponding device shows a stabilized efficiency as high as 14.81%. As far as we know, this is the highest PCE for the CsPbBrI2 perovskite based solar cells.