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Cs2AgBiBr6, as a benchmark lead‐free double perovskite, has emerged as a promising alternative to lead‐based perovskites because of its high stability, non‐toxicity, exceptional optoelectronic properties, and multifunctionality. To encourage further research on Cs2AgBiBr6 and its broad applications, in this review, its fundamental properties including the structure‐property relation, synthesis, stability, origin of absorption and photoluminescence, electron‐phonon coupling, role of defects, charge carrier dynamics, and bandgap modulation are comprehensively emphasized. The recent progress on the wide applications including solar cells, light/X‐ray detectors, and ferroelectric/magnetic devices are highlighted. Moreover, the challenges of Cs2AgBiBr6 materials and related applications are discussed and perspectives are provided for guiding the future development of this research area. [ABSTRACT FROM AUTHOR]

Tin (Sn) is a potential replacement for lead in organic–inorganic perovskite solar cell (PVSC) technology due to the attractive optoelectronic properties of Sn-perovskites. However, the poor stability of Sn2+ ions is still the main hindrance for achieving highly stable and efficient Sn-based PVSCs. In this work, anilinium hypophosphite (AHP) is introduced as a co-additive into a Sn-absorber perovskite precursor containing the tin fluoride (SnF2) additive. The incorporation of the AHP additive not only prohibits the phase separation of SnF2 but also passivates the perovskite films and finally results in absorbers with superior structural and optoelectronic properties. The underlying reason is related to the formation of a double-salt complex (Sn(H2PO2)2·SnF2) through the interaction between AHP and SnF2. The high quality of the absorber film induced by AHP delivers an improved device power conversion efficiency (PCE) with a higher open-circuit voltage than those without the AHP additive. More importantly, the device with the AHP additive can retain up to 97% of its PCE after 30 days of storage in a glovebox. [ABSTRACT FROM AUTHOR]

[Display omitted] • Anilinium hypophosphite was used as a co-additive in FASnI 3 perovskite. • Anilinium hypophosphite improved the perovskite optoelectronic properties. • Enhanced photovoltaic performance was obtained using new additive. Tin (Sn) is a promising substitute for lead (Pb) in organic–inorganic hybrid halide perovskite-photovoltaic devices, but it is prone to delivering low power conversion efficiencies (PCEs) due to the poor quality of Sn-perovskite films. In this work, anilinium hypophosphite (AHP) co-additive is used to fabricate high-quality FASnI 3 (FA+: formamidinium) perovskite films with suppressed phase-segregation and prolonged charge carrier lifetime. Perovskite films containing 0.05 M AHP are used to fabricate solar cells and deliver improved power conversion efficiency (PCE) of up to 5.48% (control devices: 4.04%). AHP eliminates the phase separation caused by SnF 2 in the absorber, leading to films with enhanced optoelectronic properties, hence the high performance of AHP-based devices. [ABSTRACT FROM AUTHOR]

Lead halide perovskite has become a promising candidate for high-performance photodetectors (PDs) due to its attractive optical and electrical properties, such as high optical absorption coefficient, high carrier mobility, and long carrier diffusion length. However, the presence of highly toxic lead in these devices has limited their practical applications and even hindered their progress toward commercialization. Therefore, the scientific community has been committed to searching for low-toxic and stable perovskite-type alternative materials. Lead-free double perovskite, which is still in the preliminary stage of exploration, has achieved inspiring results in recent years. In this review, we mainly focus on two types of lead-free double perovskite based on different Pb substitution strategies, including A2M(I)M(III)X6 and A2M(IV)X6. We review the research progress and prospects of lead-free double perovskite photodetectors in the past three years. More importantly, from the perspective of optimizing the inherent defects in materials and improving device performance, we propose some feasible pathways and make an encouraging perspective for the future development of lead-free double perovskite photodetectors. [ABSTRACT FROM AUTHOR]

Perovskite solar cells have developed rapidly in recent years as the third generation solar cells. In spite of the great improvement achieved, there still exist some issues such as undesired hysteresis and indispensable high temperature process. In this work, bulk heterojunction perovskite-phenyl-C 61 -butyric acid methyl ester solar cells have been prepared to diminish hysteresis using a facile two step spin-coating method. Furthermore, high quality tin oxide films are fabricated using pulse laser deposition technique at room temperature without any annealing procedure. The as fabricated tin oxide film is successfully applied in bulk heterojunction perovskite solar cells as a hole blocking layer. Bulk heterojunction devices based on room temperature tin oxide exhibit almost hysteresis-free characteristics with power conversion efficiency of 17.29% and 14.0% on rigid and flexible substrates, respectively. [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]