Br Perovskite Solar Cells Research Articles

Redox-inactive samarium(III) acetylacetonate as dopant enabling cation substitution and interfacial passivation for efficient and stable CsPbI2Br perovskite solar cells

All-inorganic (CsPbX3) perovskites by replacing the volatile organic components with cesium cations allow extending the long-term thermal stability of perovskite solar cells (PeSCs) vs their organic–inorganic hybrid counterparts. However, the stability of α-CsPbI3 and α-CsPbI2Br still remains to be improved. In this work, we incorporate redox-inactive samarium acetylacetonate [Sm(acac)3] into CsPbI2Br to fabricate CsPbI2Br perovskite thin films. It is evidenced that Sm3+ not only partially substitute the Pb2+ sites to yield slightly contracted perovskite lattice but also modulate the perovskite growth and passivate the NiOx/CsPbI2Br interface. As a result, CsPbI2Br PeSCs based on stoichiometric and optimal Sm(acac)3 doping (0.15 mol. %) of CsPbI2Br show excellent photovoltaic metrics with a champion power conversion efficiency (PCE) of 12.86%. Moreover, the CsPbI2Br PeSCs exhibit enhanced thermal stability upon incorporation of Sm(acac)3, which retains 90% of their original PCE under heating at 85 °C for 200 h.

Controlled n‐Doping in Air‐Stable CsPbI2Br Perovskite Solar Cells with a Record Efficiency of 16.79%

AbstractCesium‐based inorganic perovskites, such as CsPbI2Br, are promising candidates for photovoltaic applications owing to their exceptional optoelectronic properties and outstanding thermal stability. However, the power conversion efficiency of CsPbI2Br perovskite solar cells (PSCs) is still lower than those of hybrid PSCs and inorganic CsPbI3 PSCs. In this work, passivation and n‐type doping by adding CaCl2 to CsPbI2Br is demonstrated. The crystallinity of the CsPbI2Br perovskite film is enhanced, and the trap density is suppressed after adding CaCl2. In addition, the Fermi level of the CsPbI2Br is changed by the added CaCl2 to show heavy n‐type doping. As a result, the optimized CsPbI2Br PSC shows a highest open circuit voltage of 1.32 V and a record efficiency of 16.79%. Meanwhile, high air stability is demonstrated for a CsPbI2Br PSC with 90% of the initial efficiency remaining after more than 1000 h aging in air.

Inverted All-Inorganic CsPbI2Br Perovskite Solar Cells with Promoted Efficiency and Stability by Nickel Incorporation

All-inorganic CsPbI2Br perovskite solar cell with an inverted architecture of indium-tin oxide/poly[3-(4-carboxylbutyl)thiophene]/CsPbI2Br/(6,6)-phenyl-C61-butyric acid methyl ester/C60/bathocuproi...

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.

Minimizing Voltage Loss in Efficient All-Inorganic CsPbI2Br Perovskite Solar Cells through Energy Level Alignment

All-inorganic CsPbI2Br, prized for its strong stability against thermal aging and light soaking, has attracted intensive attention. However, a large energy loss results from the serious energy leve...

A Novel Anion Doping for Stable CsPbI2Br Perovskite Solar Cells with an Efficiency of 15.56% and an Open Circuit Voltage of 1.30 V

AbstractThe Cs‐based inorganic perovskite solar cells (PSCs), such as CsPbI2Br, have made a striking breakthrough with power conversion efficiency (PCE) over 16% and potential to be used as top cells for tandem devices. Herein, I− is partially replaced with the acetate anion (Ac−) in the CsPbI2Br framework, producing multiple benefits. The Ac− doping can change the morphology, electronic properties, and band structure of the host CsPbI2Br film. The obtained CsPbI2−x Br(Ac)x perovskite films present lower trap densities, longer carrier lifetimes, and fast charge transportation compared to the host CsPbI2Br films. Interestingly, the CsPbI2−x Br(Ac)x PSCs exhibit a maximum PCE of 15.56% and an ultrahigh open circuit voltage (Voc) of 1.30 V without sacrificing photocurrent. Notably, such a remarkable Voc is among the highest values of the previously reported CsPbI2Br PSCs, while the PCE far exceeds all of them. In addition, the obtained CsPbI2−x Br(Ac)x PSCs exhibit high reproducibility and good stability. The stable CsPbI2−x Br(Ac)x PSCs with high Voc and PCE are desirable for tandem solar cell applications.

A High Mobility Conjugated Polymer Enables Air and Thermally Stable CsPbI2Br Perovskite Solar Cells with an Efficiency Exceeding 15%

AbstractInorganic cesium lead halide perovskite solar cells (PSCs), such as CsPbI2Br, have made a striking breakthrough with a power conversion efficiency of over 16%. However, CsPbI2Br is known to be very sensitive to moisture, and the intrinsic long‐term stability of CsPbI2Br film remains a critical challenge. Interface engineering has been proven to be an effective way for solving the instability‐to‐moisture issue and enhancing the performance of inorganic–organic hybrid PSCs, while there are a few reports on interface engineering for inorganic PSCs. Here, a conjugated polymer, poly(N‐alkyldiketopyrrolo‐pyrrole dithienylthieno[3,2‐b]thio‐phene) (DPP‐DTT), with high mobility is introduced as a novel interface passivation for CsPbI2Br PSCs, which can significantly reduce nonradiative recombination in perovskite, leading to significant enhancement in both efficiency and stability of CsPbI2Br PSCs. Through DPP‐DTT passivation, a champion efficiency of 15.14% is obtained in CsPbI2Br PSCs. Moreover, the Lewis base DPP‐DTT can serve as an ultrahydrophobic agent to hold the photovoltaic performance of CsPbI2Br PSCs under ambient environment with humidity or thermal stress. These results provide a simple while highly effective route of fabricating the highly efficient and stable inorganic PSCs.

Synergy of Hydrophobic Surface Capping and Lattice Contraction for Stable and High‐Efficiency Inorganic CsPbI2Br Perovskite Solar Cells

CsPbI2Br has been recognized as a promising material for photovoltaic applications due to its excellent optoelectronic properties and compositional stability. Unfortunately, its desired perovskite phase is not stable in humid environments as it is spontaneously transformed into a yellow non‐perovskite phase. Herein, we present our strategy to use phenylethylammonium chlorine (PEACl) treatment to significantly improve the moisture‐resistance of the CsPbI2Br film without compromising its high solar cell efficiency. It is found that: 1) small‐sized hydrophobic aromatic group PEA+ forms in the edge‐on orientation on the CsPbI2Br surface and 2) smaller halide Cl− is doped into the CsPbI2Br lattice during post‐annealing, leading to a smaller lattice structure with beneficial crystallization quality. Compared with the reference sample without the PEACl treatment, the present device achieves a comparable power‐conversion efficiency of 14.05% and much improved moisture resistance.

All‐Inorganic CsPb1−xGexI2Br Perovskite with Enhanced Phase Stability and Photovoltaic Performance

Compared with organic-inorganic perovskites, all-inorganic cesium-based perovskites without volatile organic compounds have gained extensive interests because of the high thermal stability. However, they have a problem on phase transition from cubic phase (active for photo-electric conversion) to orthorhombic phase (inactive for photo-electric conversion) at room temperature, which has hindered further progress. Herein, novel inorganic CsPb1-x Gex I2 Br perovskites were prepared in humid ambient atmosphere without a glovebox. The phase stability of the all-inorganic perovskite was effectively enhanced after germanium addition. In addition, the highest power conversion efficiency of 10.8 % with high open-circuit voltage (VOC ) of 1.27 V in a planar solar cell based on CsPb0.8 Ge0.2 I2 Br perovskite was achieved. Furthermore, the highest VOC up to 1.34 V was obtained by CsPb0.7 Ge0.3 I2 Br perovskite, which is a remarkable record in the field of all-inorganic perovskite solar cells. More importantly, all the photovoltaic parameters of CsPb0.8 Ge0.2 I2 Br perovskite solar cells showed nearly no decay after 7 h measurement in 50-60 % relative humidity without encapsulation.

Precursor Engineering for All‐Inorganic CsPbI2Br Perovskite Solar Cells with 14.78% Efficiency

AbstractThe optoelectronic properties of perovskite films are closely related to the film quality, so depositing dense, uniform, and stable perovskite films is crucial for fabricating high‐performance perovskite solar cells (PSCs). CsPbI2Br perovskite, prized for its superb stability toward light soaking and thermal aging, has received a great deal of attention recently. However, the air instability and poor performance of CsPbI2Br PSCs are hindering its further progress. Here, an approach is reported for depositing high‐quality CsPbI2Br films via the Lewis base adducts PbI2(DMSO) and PbBr2(DMSO) as precursors to slow the crystallization of the perovskite film. This process produces CsPbI2Br films with large‐scale crystalline grains, flat surfaces, low defects, and long carrier lifetimes. More interestingly, PbI2(DMSO) and PbBr2(DMSO) adducts could significantly improve the stability of CsPbI2Br films in air. Using films prepared by this technique, a power conversion efficiency (PCE) of 14.78% is obtained in CsPbI2Br PSCs, which is the highest PCE value reported for CsPbI2Br‐based PSCs to date. In addition, the PSCs based on DMSO adducts show an extended operational lifetime in air. These excellent performances indicate that preparing high‐quality inorganic perovskite films by using DMSO adducts will be a potential method for improving the performance of other inorganic PSCs.

Interface Engineering for All-Inorganic CsPbI2 Br Perovskite Solar Cells with Efficiency over 14.

In this work, a SnO2 /ZnO bilayered electron transporting layer (ETL) aimed to achieve low energy loss and large open-circuit voltage (Voc ) for high-efficiency all-inorganic CsPbI2 Br perovskite solar cells (PVSCs) is introduced. The high-quality CsPbI2 Br film with regular crystal grains and full coverage can be realized on the SnO2 /ZnO surface. The higher-lying conduction band minimum of ZnO facilitates desirable cascade energy level alignment between the perovskite and SnO2 /ZnO bilayered ETL with superior electron extraction capability, resulting in a suppressed interfacial trap-assisted recombination with lower charge recombination rate and greater charge extraction efficiency. The as-optimized all-inorganic PVSC delivers a high Voc of 1.23 V and power conversion efficiency (PCE) of 14.6%, which is one of the best efficiencies reported for the Cs-based all-inorganic PVSCs to date. More importantly, decent thermal stability with only 20% PCE loss is demonstrated for the SnO2 /ZnO-based CsPbI2 Br PVSCs after being heated at 85 °C for 300 h. These findings provide important interface design insights that will be crucial to further improve the efficiency of all-inorganic PVSCs in the future.

All-Inorganic CsPbI2Br Perovskite Solar Cells with High Efficiency Exceeding 13.

All-inorganic perovskite solar cells provide a promising solution to tackle the thermal instability problem of organic-inorganic perovskite solar cells (PSCs). Herein, we designed an all-inorganic perovskite solar cell with novel structure (FTO/NiO x/CsPbI2Br/ZnO@C60/Ag), in which ZnO@C60 bilayer was utilized as the electron-transporting layers that demonstrated high carrier extraction efficiency and low leakage loss. Consequently, the as-fabricated all-inorganic CsPbI2Br perovskite solar cell yielded a power conversion efficiency (PCE) as high as 13.3% with a Voc of 1.14 V, Jsc of 15.2 mA·cm-2, and FF of 0.77. The corresponding stabilized power output (SPO) of the device was demonstrated to be ∼12% and remarkably stable within 1000 s. Importantly, the obtained all-inorganic PSCs without encapsulation exhibited only 20% PCE loss with thermal treatment at 85 °C for 360 h, which largely outperformed the organic-species-containing PSCs. The present study demonstrates potential in overcoming the intractable issue concerning the thermal instability of perovskite solar cells.