Hybrid perovskites have shown astonishing power conversion efficiencies owed to their remarkable absorber characteristics including long carrier lifetimes, and a relatively substantial defect tolerance for solution-processed polycrystalline films. However, nonradiative charge carrier recombination at grain boundaries limits open circuit voltages and consequent performance improvements of perovskite solar cells. Here we address such recombination pathways and demonstrate a passivation effect through guanidinium-based additives to achieve extraordinarily enhanced carrier lifetimes and higher obtainable open circuit voltages. Time-resolved photoluminescence measurements yield carrier lifetimes in guanidinium-based films an order of magnitude greater than pure-methylammonium counterparts, giving rise to higher device open circuit voltages and power conversion efficiencies exceeding 17%. A reduction in defect activation energy of over 30% calculated via admittance spectroscopy and confocal fluorescence intensity mapping indicates successful passivation of recombination/trap centers at grain boundaries. We speculate that guanidinium ions serve to suppress formation of iodide vacancies and passivate under-coordinated iodine species at grain boundaries and within the bulk through their hydrogen bonding capability. These results present a simple method for suppressing nonradiative carrier loss in hybrid perovskites to further improve performances toward highly efficient solar cells.

Nowadays the major factors determining commercialization of lead halide perovskite photovoltaic technology are shifting from solar cell performance to stability, reproducibility, up-scaling, and in particular the concern of Pb leakage during solar cell operation. Here we simulate a realistic scenario that the perovskite solar modules with different encapsulation methods are damaged to a typical extent by mechanical impact (according to the modified FM 44787 standard) and quantitatively measure the lead leakage rates from the damaged modules. We demonstrate that an epoxy resin (ER) based encapsulation method reduces the Pb leakage rate by a factor of 375 compared to the encapsulation method using a glass cover with the UV-resin cured at the module edges. The excellent Pb leakage prevention characteristics is due to the self-healing property of ER and increased mechanical strength. These findings strongly suggest lead halide perovskite photovoltaic products can be used with minimal Pb leakage if appropriate encapsulation is employed.

Minimization of defects in absorber materials is essential for hybrid perovskite solar cells, especially when constructing thick polycrystalline layers in a planar configuration. Here, a simple methylamine solution-based additive is reported to improve film quality with nearly an order of magnitude reduction in intrinsic defect concentration. In the resultant film, an increase in carrier lifetime as a result of a decrease in shallow electronic disorder is observed. This superior crystalline film quality is further evidenced via a doubled spin relaxation time as compared with other reports. Bearing sufficient carrier diffusion length, a thick absorber layer (≈650 nm) is implemented in planar devices to achieve a champion power conversion efficiency of 20.02% with a stabilized output efficiency of 19.01% under one sun illumination. This work demonstrates a simple approach to improve hybrid perovskite film quality by substantial reduction of intrinsic defects for wide applications in optoelectronics.

Upscaling of perovskite solar cells to module scale and affording long-term stability have been recognized as the most important challenges for commercialization of this emerging photovoltaic technology. In a perovskite solar module (PSM), each interface within the device contributes to the efficiency and stability. Here, we employ a holistic interface stabilization strategy by modifying all the relevant layers and interfaces, namely the perovskite layer, charge transporting layers and the device encapsulation to improve the efficiency and stability of PSMs. The treatments were selected to be compatible with low-temperature scalable processing and the module scribing steps. Our unencapsulated PSM achieved a reverse-scan efficiency of 16.6% with a designated area of 22.4 cm 2 . The encapsulated PSM retained approximately 86% 2 of the initial performance after continuous operation for 2000 h under AM 1.5G light illumination, with translates into a T 90 lifetime of 1570 h and an estimated T 80 lifetime of 2680 h.

In this study, we communicate an investigation on efficient CH3NH3PbI3-based solar cells with carbon electrode using mesoporous TiO2 and NiO layers as electron and hole selective contacts. The device possesses an appreciated power conversion efficiency of 14.9% under AM 1.5G illumination. The detailed information can be disclosed with impedance spectroscopy via tuning the interfaces between CH3NH3PbI3 and different charge selective contacts. The results clearly show charge accumulation at the interface of CH3NH3PbI3. The NiO is believed to efficiently accelerate charge extraction to the external circuit. The extracted charge could improve photovoltaic performance by shifting hole Fermi level down, achieving a high device photovoltage. A fast interfacial recombination at the interface of CH3NH3PbI3/electron selective contact layer (mesoporous TiO2), occurring in millisecond domains, is the critical issue for charge carrier recombination loss.

In this work all‐inorganic perovskite CsPbIBr2 are doped with Mn to compensate their shortcomings in band structure for the application of perovskite solar cells (PSCs). The novel Mn‐doped all‐inorganic perovskites, CsPb1−xMnxI1+2xBr2−2x, are prepared in ambient atmosphere. As the concentration of Mn2+ ions increases, the bandgaps of CsPb1−xMnxI1+2xBr2−2x decrease from 1.89 to 1.75 eV. Additionally, when the concentration of Mn dopants is appropriate, this novel Mn‐doped all‐inorganic perovskite film shows better crystallinity and morphology than its undoped counterpart. These advantages alleviate the energy loss in hole transfer and facilitate the charge‐transfer in perovskites, therefore, PSCs based on these novel CsPb1−xMnxI1+2xBr2−2x perovskite films display better photovoltaic performance than the undoped CsPbIBr2 perovskite films. The reference CsPbIBr2 cell reaches a power conversion efficiency (PCE) of 6.14%, comparable with the previous reports. The CsPb1−xMnxI1+2xBr2−2x cells reach the highest PCE of 7.36% (when x = 0.005), an increase of 19.9% in PCE. Furthermore, the encapsulated CsPb0.995Mn0.005I1.01Br1.99 cells exhibit good stability in ambient atmosphere. The storage stability measurements on the encapsulated PSCs reveal that PCE is dropped by only 8% of the initial value after >300 h in ambient. Such improved efficiency and stability are achieved using low‐cost carbon electrodes (without expensive hole transport materials and Au electrodes).

In the past decade, the efficiency of perovskite solar cells quickly increased from 3.8% to 25.2%. The quality of perovskite films plays vital role in device performance. The films fabricated by solution‐process are usually polycrystalline, with significantly higher defect density than that of single crystal. One kind of defect in the films is uncoordinated Pb2+, which is usually generated during thermal annealing process due to the volatile organic component. Another detrimental kind of defect is Pb0, which is often observed during the film fabrication process or solar cell operation. Because the open circuit voltage has a close relation with the defect density, it is thus desirable to passivate these two kinds of defects. Here, a molecule with multiple ligands is introduced, which not only passivates the uncoordinated Pb2+ defects, but also suppresses the formation of Pb0 defects. Meanwhile, such a treatment improves the energy level alignment between the valence band of perovskite and the highest occupied molecular orbital of spiro‐OMeTAD. As a result, the performance of perovskite solar cells significantly increases from 19.0% to 21.4%.

The coordination effects of additives during perovskite crystal growth are investigated, and a novel technique to fabricate high-quality perovskite thin films by introduction of weak coordination additives (e.g., acetonitrile) in the precursors is demonstrated.