Formamidinium lead iodide perovskites are promising light-harvesting materials, yet stabilizing them under operating conditions without compromising optimal optoelectronic properties remains challenging. We report a multimodal host–guest complexation strategy to overcome this challenge using a crown ether, dibenzo-21-crown-7, which acts as a vehicle that assembles at the interface and delivers Cs+ ions into the interior while modulating the material. This provides a local gradient of doping at the nanoscale that assists in photoinduced charge separation while passivating surface and bulk defects, stabilizing the perovskite phase through a synergistic effect of the host, guest, and host–guest complex. The resulting solar cells show power conversion efficiencies exceeding 24% and enhanced operational stability, maintaining over 95% of their performance without encapsulation for 500 h under continuous operation. Moreover, the host contributes to binding lead ions, reducing their environmental impact. This supramolecular strategy illustrates the broad implications of host–guest chemistry in photovoltaics.
The
synthesis of dipotassio-2,5-bis(trialkylsilyl)silacyclopentadienediides
K2[3] and germacyclopentadienediides K2[4] is reported. The prepared silole dianions, 3, are characterized by a significantly deshielded silicon
nuclei with 29Si NMR signals at very unusual low field
positions for silicon anions (δ29Si = 148–169).
The results of DFT calculations revealed that this deshielding is
a consequence of the silylene-like frontier orbitals of silole dianions 3 and efficient hyperconjugation between the trialkylsilyl-substituents
and the cyclic delocalized π-system. Solid-state structure determinations
of potassium salts of silole and germole dianions revealed a novel
polymeric bis-η5,bis-η1-coordination
mode between heterole and potassium ions.
The synthesis of a bicyclic germylene from the reaction of a germole dianion with hafnocene dichloride is reported. This germylene is stabilized by a homoconjugative interaction of the dicoordinated germanium atom with a remote C=C double bond. First reactivity studies revealed its nucleophilic character and resulted in the synthesis of bimetallic hafnium/iron and hafnium/tungsten complexes with a germylene group linker.
Carbenes as single electron donors: the tritylation of N-heterocyclic carbenes proceeds via an initial SET step, giving highly reactive carbene radical cations and the trityl radical.
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