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Great efforts have been made to improve the composition and structure of perovskite light‐emitting diodes (PeLEDs) through methods such as dimensional reduction or halide engineering, thereby reducing non‐radiative recombination. However, deep‐blue PeLEDs still face a deep valence band issue. The mismatched energy level alignment between the perovskite and the hole transport layer (HTL) leads to charge accumulation, resulting in imbalanced carrier transport and injection. Herein, to address the issues of imbalanced carrier injection and defect states in PeLEDs, a deep‐blue perovskite emitter using [4‐(3,6‐Dimethyl‐9H‐carbazol‐9‐yl)butyl]phosphonic acid (Me‐4PACz) as the material to promote hole transport and passivate defects is presented. The stepwise energy level structure design can effectively reduce the hole injection barrier and improve the carrier injection efficiency. Additionally, the electron‐rich P═O bond can effectively passivate the unsaturated Pb2+ in perovskite, reducing non‐radiative recombination caused by defects. Ultimately, stable deep‐blue PeLEDs (≈458 nm) are successfully fabricated with an external quantum efficiency (EQE) of 4.33%. This study provides new insights into the application of self‐assembled monolayers (SAMs) in PeLEDs. [ABSTRACT FROM AUTHOR]

The device performance of deep‐blue perovskite light‐emitting diodes (PeLEDs) is primarily constrained by low external quantum efficiency (EQE) especially poor operational stability. Herein, we develop a facile strategy to improve deep‐blue emission through rational interface engineering. We innovatively reported the novel electron transport material, 4,6‐Tris(4‐(diphenylphosphoryl)phenyl)‐1,3,5‐triazine (P‐POT2T), and utilized a sequential wet‐dry deposition method to form the homogenic gradient interface between electron transport layer (ETL) and perovskite surface. Unlike previous reports that achieved carrier injection balance by inserting new interlayers, our strategy not only passivated uncoordinated Pb2+ in the perovskite via P=O functional groups but also reduced interfacial carrier recombination without introducing new interfaces. Additionally, this strategy enhanced the interface contact between the perovskite and ETL, significantly boosting device stability. Consequently, the fabricated deep‐blue PeLEDs delivered an EQE exceeding 5 % (@ 460 nm) with an exceptional halftime extended to 31.3 minutes. This straightforward approach offers a new strategy to realize highly efficient especially stable PeLEDs. [ABSTRACT FROM AUTHOR]

Inverted (p‐i‐n) perovskite solar cells (PSCs) have experienced remarkable advancements in recent years, which is largely attributed to the development of novel hole‐transport layer (HTL) self‐assembled monolayer (SAM) materials. Methoxy (MeO−) groups are typically introduced into SAM materials to enhance their wettability and effectively passivate the perovskite buried interface. However, MeO‐based SAM materials exhibit a mismatch in highest occupied molecular orbital (HOMO) levels with perovskite layer due to the strong electron‐donating capability of methoxy group. In this work, we introduced a methylthio (MeS−) substituent that is superior to methoxy as a highly versatile self‐assembled molecular design strategy. As a soft base, sulfur atom forms a stronger Pb−S bond than oxygen. Additionally, within the CbzPh series of SAM materials, MeS−CbzPh demonstrates a more optimal HOMO level and enhanced hole transport properties. Consequently, the MeS−CbzPh HTL based device achieved an impressive power conversion efficiency (PCE) of 26.01 % and demonstrated high stability, retaining 93.3 % efficiency after 1000 hours of maximum power point tracking (MPPT). Moreover, in comparison with the commonly used 4PACz‐based SAM molecular series, MeS‐4PACz also exhibited the best performance among its peers. Our work provides valuable insights for the molecular design of SAM materials, offering a highly versatile functional substituent group. [ABSTRACT FROM AUTHOR]

Achieving high‐efficiency perovskite solar cells (PSCs) hinges on the precise control of the perovskite film crystallization process, often improved by the inclusion of additives. While dimethyl sulfoxide (DMSO) is traditionally used to manage this process, its removal from the films is problematic. In this work, methyl phenyl sulfoxide (MPSO) was employed instead of DMSO to slow the crystallization rate, as MPSO is more easily removed from the perovskite structure. The electron delocalization associated with the benzene ring in MPSO decreases the electron density around the oxygen atom in the sulfoxide group, thus reducing its interaction with PbI2. This strategy not only sustains the formation of a crystallization‐slowing intermediate phase but also simplifies the elimination of the additive. Consequently, the optimized PSCs achieved a leading power conversion efficiency (PCE) of 25.95 % along with exceptional stability. This strategy provides a novel method for fine‐tuning perovskite crystallization to enhance the overall performance of photovoltaic devices. [ABSTRACT FROM AUTHOR]

The effective utilization of self‐assembled monolayers (SAMs) has indeed resulted in significant improvement in the power conversion efficiency (PCE) of inverted perovskite solar cells (PSCs). However, the poor interface contact between self‐assembled monolayer (SAM) and perovskite layers limits the further improvement of inverted PSCs. Herein, polyaniline is employed as a conductive adhesive, enabling interaction with the perovskite and simultaneous coupling with the SAM, to optimize the buried interface contact. Furthermore, the adhesive strategy is validated to alleviate residual tensile strain at the buried interface using the non‐destructive back grazing‐incidence wide‐angle X‐ray scattering (BGIWAXS) technique. As a result, the optimized inverted PSCs achieve a champion PCE of 25.59% with impressive stability by retaining 97.3% of its initial efficiency after 1200 h under ambient conditions and light‐emitting diode illumination. The findings provide a facial adhesive bridging strategy to play more impressive functions in the SAM‐based inverted PSCs. [ABSTRACT FROM AUTHOR]

Currently, the power conversion efficiency (PCE) of inverted perovskite solar cells (PSCs) is still limited by reduced open-circuit voltage (V OC ), due to defect-induced charge recombination. Most studies focus on defect passivation and improving carrier transport through introducing passivating molecules or macroscopic physical fields. Herein, to mitigate energy level mismatch and recombination losses induced by interface defects, an interface electric-field passivation is introduced, employing the ordered arrangement of the dipole molecule benzenesulfonyl chloride (BC). An enhanced V OC is achieved without the introduction of an external physical field, owing to the interfacial dipole field effect and chemical passivation by BC. Subsequently, an inverted device with a PCE of 25.41% is obtained, alongside exceptional stability, retaining 95% of the initial efficiency after 1157 h. This work demonstrates the effective dipole-induced interfacial field-effect passivation in inverted PSCs and contributes to further advancements in the efficiency and stability of inverted devices., (© 2024 Wiley‐VCH GmbH.)

The device performance of deep-blue perovskite light-emitting diodes (PeLEDs) is primarily constrained by low external quantum efficiency (EQE) especially poor operational stability. Herein, we develop a facile strategy to improve deep-blue emission through rational interface engineering. We innovatively reported the novel electron transport material, 4,6-Tris(4-(diphenylphosphoryl)phenyl)-1,3,5-triazine (P-POT2T), and utilized a sequential wet-dry deposition method to form the homogenic gradient interface between electron transport layer (ETL) and perovskite surface. Unlike previous reports that achieved carrier injection balance by inserting new interlayers, our strategy not only passivated uncoordinated Pb 2+ in the perovskite via P=O functional groups but also reduced interfacial carrier recombination without introducing new interfaces. Additionally, this strategy enhanced the interface contact between the perovskite and ETL, significantly boosting device stability. Consequently, the fabricated deep-blue PeLEDs delivered an EQE exceeding 5 % (@ 460 nm) with an exceptional halftime extended to 31.3 minutes. This straightforward approach offers a new strategy to realize highly efficient especially stable PeLEDs., (© 2024 Wiley-VCH GmbH.)