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Reducing the energy loss and retarding the carrier recombination at the interface are crucial to improve the performance of the perovskite solar cell (PSCs). However, little is known about the recombination mechanism at the interface of anode and SnO2 electron transfer layer (ETL). In this work, an ultrathin wide bandgap dielectric MgO nanolayer is incorporated between SnO2:F (FTO) electrode and SnO2 ETL of planar PSCs, realizing enhanced electron transporting and hole blocking properties. With the use of this electrode modifier, a power conversion efficiency of 18.23% is demonstrated, an 11% increment compared with that without MgO modifier. These improvements are attributed to the better properties of MgO‐modified FTO/SnO2 as compared to FTO/SnO2, such as smoother surface, less FTO surface defects due to MgO passivation, and suppressed electron–hole recombinations. Also, MgO nanolayer with lower valance band minimum level played a better role in hole blocking. When FTO is replaced with Sn‐doped In2O3 (ITO), a higher power conversion efficiency of 18.82% is demonstrated. As a result, the device with the MgO hole‐blocking layer exhibits a remarkable improvement of all J–V parameters. This work presents a new direction to improve the performance of the PSCs based on SnO2 ETL by transparent conductive electrode surface modification. [ABSTRACT FROM AUTHOR]

Although the perovskite solar cells (PSCs) based on organic hole transport materials (HTMs) have demonstrated excellent photovoltaic performance, there are still some obstacles that limiting their future commercialization, one of which is the device stability. Herein, we first report that depositing a (200) orientated PbS thin film upon organic HTMs as buffer layer can significantly enhance the stability and improve the performance of PSCs. The superior hole extraction efficiency of spiro-OMeTAD/PbS bilayer can balance the charge transfer and the hydrophobic nature of PbS could avoid the permeation of moisture. As a result, the PSCs with PbS buffer layer exhibited a better photovoltaic performance (a champion power conversion efficiency of 19.58%) with respect to the reference cells (18.79%), and maintained almost 100% of its initial PCE after 1000 h stored in ambient air. Furthermore, when suffer from some more severe conditions, the device with PbS retained 56% of its initial PCE after 96 h annealing at 85 °C, while only 25% for the reference cells. Our results provide a simple method to avoid the weakness of organic HTMs, and suggest that PbS thin film could be an alternative buffer layer material in PSCs to simultaneously improve the device stability and photovoltaic performance. [ABSTRACT FROM AUTHOR]

Perovskite Solar Cells: In Situ Defect Passivation with Silica Oligomer for Enhanced Performance and Stability of Perovskite Solar Cells (Adv. In article number 1901716, Hongwei Lei, Song Zhang, Zuojun Tan, and co-workers report a novel and efficient perovskite defect passivation strategy using silica oligomer. Silica oligomer PA can enlarge perovskite grain sizes, prolong carrier lifetime, enhance charge carrier dynamics and reduce trap state densities, resulting in highly efficient PVSCs with good humid and thermal stability. [Extracted from the article]

Perovskite solar cells (PVSCs) have achieved excellent power conversion efficiency (PCE) but still suffer from instability issues. Defect passivation is an important route to simultaneously increase the efficiency and stability of PVSCs. Here, a strategy of incorporating silica oligomer in perovskite films for surface and grain boundary defect passivation is reported. Silica oligomer passivation agent (PA) is in situ formed through hydrolysis and condensation reaction of tetraethyl orthosilicate additive in perovskite precursor. The passivation mechanism is elucidated by density functional theory calculation, revealing stable chelating interaction and hydrogen bond interaction between PA and perovskite. Spectroscopic and electrical characterizations demonstrate that silica oligomer can enlarge grain sizes, prolong carrier lifetime, enhance charge carrier dynamics, and reduce trap state densities in perovskite films. Planar PVSCs with passivation achieve a highly improved PCE of 19.64% with a stabilized efficiency of 18.81%. More importantly, unencapsulated perovskite devices with passivation retain nearly 90% of original efficiency after 1000 h storage under ambient condition and sustained 87% of initial performance after high‐temperature (120 °C) thermal accelerated aging, showing highly enhanced moisture and thermal stability. Therefore, the present study provides a pathway to the future design and optimization of PVSCs with higher efficiency and greater stability. [ABSTRACT FROM AUTHOR]

Ternary oxides Fe 2-x Mg x O 3 is introduced to passivate the perovskite/SnO 2 QDs interface, trigger the heterogeneous nucleation for uniform perovskite films, and increase the interface contact for the rapid electron transfer. Consequently, the corresponding perovskite solar cell achieves a champion efficiency over 21%. [Display omitted] • Fe 2-x Mg x O 3 is introduced to passivate the perovskite/SnO 2 interface. • The interaction between perovskite and Fe 2-x Mg x O 3 triggers a heterogeneous nucleation. • Flocculent Fe 2-x Mg x O 3 increase the contact with perovskite for electron transfer. • The interaction between Fe 2-x Mg x O 3 and SnO 2 QD passivates the defects. • Fe 1.84 Mg 0.16O 3 -based PSC achieves a champion efficiency over 21% with negligible J–V hysteresis. Interface function material has been widely used to reduce interfacial potential barrier for enhanced charge-dynamics and photovoltaic properties of perovskite solar cells (PSCs). Herein, ternary oxides Fe 2-x Mg x O 3 are introduced to passivate the perovskite/SnO 2 quantum dots (QDs) interface. The interaction between perovskite and Fe 2-x Mg x O 3 could trigger a heterogeneous nucleation for the uniform perovskite photoactive layer. The flocculent Fe 2-x Mg x O 3 also increase the interface contact with perovskite enabling more transferring channel of electron, and decrease the interface-defects with smaller the energy level offset at this interface. Such oxide bridges between perovskite and SnO 2 QD could effectively enhance electron transfer. Consequently, a Fe 1.84 Mg 0.16 O 3 -based PSC is achieved with a champion efficiency over 21% and negligible J–V hysteresis. [ABSTRACT FROM AUTHOR]