Li@C₆₀ endohedral fullerene as a supraatomic dopant for C₆₀ electron-transporting layers promoting the efficiency of perovskite solar cells

Abstract

C60:Li@C60 hybrid n-type semiconducting films were first fabricated.

Endocircular Li Carbon Rings

“…[23] Encapsulating or accommodating guest atoms by carbon allotropes,l ike fullerenes, [24] graphenes, [25] and carbon nanotubes, [26] are well-accepted ways to extend the range of applicability.W ec oncentrate here on alkali atoms as guest atoms.T here are many investigations on carbon allotropes with alkali guest atoms, [24][25][26][27][28][29][30][31][32] which show that they possess interesting geometrical and electronic structures and have much potential for applications.H ere,w eb riefly mention solar cells, [33,34] superconductive agents, [35,36] and supercapacitors. [37,38] As shown in our previous accurate numerical studies,t he electronic structures of endohedral alkali fullerenes vary with different sizes of carbon cages and different alkali atoms.E ndohedral alkali fullerenes can form chargeseparated (CS) electronic states [28,31,[39][40][41][42] as well as noncharge-separated states like caged-electron (CE) [32] and splitelectron (SE) [43] states.S urprisingly,t ot he best of our knowledge nothing is known on carbon rings encircling ag uest atom like Li or other alkalies.D os uch endocircular systems exist as stable entities and if yes which kind of electronic states do they support?…”

Direct Visualization of Nearly Free Electron States Formed by Superatom Molecular Orbitals in a Li@C60 Monolayer

“…To make this possible, we exploit a new salt containing bis­(trifluoro­methyl­sulfonyl)­imide NTf 2 – , namely [Li + @C 60 ]­NTf 2 – . In this salt, the Coulombic interaction between the cationic Li + @C 60 and the anionic NTf 2 – becomes significantly weaker compared to that in the case of [Li + @C 60 ]­PF 6 – because the ion radius of NTf 2 – is much larger than that of PF 6 – . − The weak Coulombic interaction may so reduce the desorption of Li during the vacuum deposition process. In this work, we were indeed able to form a nearly pure Li@C 60 monolayer by the vacuum evaporation of [Li + @C 60 ]­NTf 2 – .…”

Environmentally Compatible Lead-Free Perovskite Solar Cells and Their Potential as Light Harvesters in Energy Storage Systems

“…Energy level alignment plays a vital role in increasing V OC . Diverse fullerene derivatives have been used to improve V OC [ 45 , 46 , 47 , 48 , 49 ]. Among them, Ning and colleagues used indene-C 60 bisadduct (ICBA) fullerene as an electron-transporting layer in inverted-type Sn-PSCs [ 50 ].…”