Design and control of organic semiconductors and their nanostructures for polymer–fullerene-based photovoltaic devices

Abstract

Development of unique conjugated polymer donors, next-generation fullerene acceptors, and one-dimensionally confined, organic donor–acceptor heterojunction nanorods for photovoltaic applications.

New generation solar cells: concepts, trends and perspectives

“…Research in the field has flourished in the last decade and the rational design of new optimized materials has led to PCEs above 10%. 17 Morphology of the blend at the nanoscale is probably the major challenge in OPVs in an effort to improve charge separation. This being a prerequisite for rationally improving performance, numerous structural characterization techniques as well as physicochemical processing approaches have been developed and carried out on heterojunction films.…”

“…Efforts mainly focused on synthetic manoeuvres to tailor their energy levels, not only for effective light-harvesting, but also for better matching of the HOMO-LUMO levels with those of the acceptor for efficient charge transfer. Hundreds of conjugated low bandgap donor-acceptor polymers, based on thiophene, fluorene, carbazole and cyclopentadithiophene among others 17,30 have been synthesized in recent years, and among those, thieno [3,4-b]thiophene-based structures have exhibited the most promising behavior, presenting optimally low bandgaps and efficiencies reaching 7-9%. 17 The most successful derivative is polythieno [3,4-b]-thiophene-co-benzodithiophene (PTB7) (Fig.…”

cis-1 Isomers of tethered bismethano[70]fullerene as electron acceptors in organic photovoltaics

“…Another strategy for developing high-performance acceptors is the use of fullerene bis-adducts. 1,13 By increasing the number of addends from one to two, the degree of pconjugation is reduced and the energy level of the lowest unoccupied molecular orbital (LUMO) is raised. Since V OC is generally proportional to the energy difference between the LUMO of the electron-acceptor and the highest occupied molecular orbital (HOMO) of the electron-donor, 1,2 the rise in the LUMO energy of electron-acceptors improves V OC .…”

“…[1][2][3][4][5] The photoactive layer generally comprises a blend lm with a bulk heterojunction (BHJ) structure of electron-donating conjugated polymers and electron-accepting organic semiconductors. Fullerene derivatives have been widely utilized as electron-acceptors 5 because of their reversible reduction behaviors, outstanding electron affinities, and excellent electron-transporting properties originating from their small reorganization energies of electron transfer, 6 whereas non-fullerene electron acceptors, exhibiting high power conversion efficiencies (PCEs), have recently emerged as alternatives.…”

Thermal Precursor Approach to Pristine Fullerene Film as Electron Selective Layer in Perovskite Solar Cells

“…31,32 In this method, a film of a highlysoluble precursor compound is formed by a solution-process such as spin-coating, and then the precursor is converted to a target semiconducting material by heating. By taking advantage of the drastic change in solubilities before and after the conversion process, this thermal precursor approach enables the construction of multi-layered structures.…”