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A New Strategy for Increasing the Efficiency of Inverted Perovskite Solar Cells to More than 21%: Higha??Humidity Induced Selfa??Passivation of Perovskite Films
摘要： The performance of perovskite solar cells (PSCs) are known to be extremely sensitive to humidity in the preparation environment. However, the main mechanism by which the moisture influences the quality of the perovskite film and the device performance is not yet completely revealed. In this work, we established a new strategy to obtain inverted PSCs with remarkable high VOC by including a high-humidity treatment and sufficient DMSO-atmosphere annealing in the preparation process. We found that the lattice distortion on the surface of perovskite grains caused by the high-humidity treatment played a key role in the self-passivation of perovskite. Inverted (p-i-n) PSCs based on the self-passivated perovskite films showed effective suppression of non-radiative recombination, which increased the device VOC to 1.17 V and achieved the highest efficiency of 21.38 %. It is expected that the findings of this work shed more light on the currently proposed mechanism governing the action of moisture on the performance of the PSCs.
关键词： Self-passivation,High open-circuit voltage,Perovskite solar cells,High-humidity,Grain boundaries
更新于2025-09-23 15:19:57
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Novel Lewis Base Cyclam Self-Passivation of Perovskites without Anti-Solvent Process for Efficient Light-Emitting Diodes
摘要： Metal halide perovskites have been focused as a candidate applied as a promising luminescent material for next-generation high-quality lighting and high-definition display. However, as perovskite film formed, high density of defects would produce in solution processing inevitably, leading to low exciton recombination efficiency in light-emitting diodes (LEDs). Herein, a facile and novel self-passivation strategy to inhibit defects formation in perovskite film for constructing high performance LEDs is developed. For the first time, we introduce 1,4,8,11-tetraazacyclotetradecane (cyclam) in perovskite precursor solution and it spontaneously passivates defect states of CsPbBr3-based perovskite by coaction between amine and uncoordinated lead ions during spin-coating without anti-solvent process. Furthermore, as a delocalized system, cyclam also possesses chemical properties that facilitate exciton transportation. The proposed passivation strategy boosts the external quantum efficiency (EQE) from 1.25% (control device) to 16.24% (cyclam-passivated device). Further, defects passivation is also conductive to reduce LED degradation paths and improve device stability as the extrapolated lifetime (T50) of LEDs at an initial brightness of 100 cd/m2 is increased from 0.9 h to 127 h. These findings indicate the introduction of cyclam is highly effective to enhance the performance of LEDs, and such strategy in effectively reducing the defects could be also applied in other perovskite-based devices, such as lasers, solar cells, and photodetectors.
关键词： perovskites,self-passivation,light-emitting diodes,defect states,Lewis base cyclam
更新于2025-09-19 17:13:59
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Ambipolar and Robust WSe <sub/>2</sub> Field‐Effect Transistors Utilizing Self‐Assembled Edge Oxides
摘要： Transition metal oxides (TMOs) with high work function (WF) show promising properties as unipolar p-type contacts for transition metal dichalcogenides. Here, ambipolar field-effect transistors (FETs) enabled by bilayer WSe2 with self-assembled TMOs (WO2.57) as contacts are reported. Systematic material characterizations demonstrate the formation of WO2.57/WSe2 heterojunctions around nanoflake edges with Se atoms substituted by O atoms after air-exposure, while pristine properties of WSe2 almost sustain in inner domains. As-fabricated FETs exhibit both polarities, implying WO2.57 with lowered WF at edges can serve as both the p-type and n-type contact for inner WSe2. Noteworthy, greatly reduced contact resistance and enhanced channel current are achieved, compared to the devices without WO2.57 contacts. Linear drain–source current relationship from 77 to 300 K indicates the ohmic contact between edge WO2.57 and inner WSe2. Density functional theory calculations further reveal that the WO2.57/WSe2 heterojunction forms a barrier-less charge distribution. These nm-scale FETs possess remarkable electrical conductivity up to ≈2600 S m?1, ultra-low leakage current down to ≈10?12 A, robustness for high voltage operation, and air stability, which even outperform pristine WSe2 FETs. Theoretical calculations reveal that the high conductivity is exclusively attributed to the air-induced WO2.57 and its further carrier injection to WSe2.
关键词： field-effect transistors,self-passivation,WOx,density functional theory,WSe2
更新于2025-09-11 14:15:04