Themed collection Editor’s Choice: Organic Photovoltaics

Associate Editors Yana Vaynzof and Renaud Demadrille highlight recent research in organic photovoltaics in this themed collection (rsc.li/OrganicPhotovoltaics).

Associate Editors Yana Vaynzof and Renaud Demadrille highlight recent research in organic photovoltaics in this themed collection (rsc.li/OrganicPhotovoltaics).

Recent advances in polymer acceptors that focus on structure–property relationships, which may provide guidance for photovoltaic materials, were systematically summarized.

An efficient approach to improve V_oc values for OSCs through molecular design and modification of photovoltaic materials was summarized and discussed.

Non-fullerene organic solar cells based on a BODIPY-polymer as electron donor provided a high photocurrent above 21 mA cm⁻² and a record efficiency of 9.86%.

A series of ternary OSCs were fabricated with PBDB-T-2Cl:IXIC-4Cl as a host system and IT-4F as the third component. The optimal ternary device achieved an excellent PCE of 15.0%.

The structural variation by just changing the linkage positions affects the molecular configuration, absorption, packing, charge transport and photovoltaic performance.

Installation of chlorine atoms into the ITIC non-fullerene acceptor enables low energy photon harvesting generating high photocurrent in OSCs when paired with PBDB-T. The active layer morphology is greatly influenced by solvent additives.

In this communication, a novel asymmetric ladder-type thiophene-phenylene-thieno[3,2-b]thiophene-fused building block TPTT and the corresponding asymmetric nonfullerene acceptor TPTT-IC were reported for the first time.

A new narrow-bandgap polymerized small molecule acceptor, namely PG1, was designed and synthesized. The optimal all-polymer solar cells (all-PSCs) based PBDB-T:PG1 achieved an outstanding PCE of 11.5% with a high V_oc of 0.94 V.

Organic solar cell shows significantly different degradation rate with different donor polymer crystallinity, even the donors and acceptors are all photostable.

ITIC photostability is markedly dependent on the specific polymorph phase and end-group decoration. Fluorination grants stronger chemical stability upon degradation.

A new narrow bandgap non-fullerene electron acceptor was designed, synthesized, and characterized for near-infrared organic photovoltaics.

The binding of a porphyrin dimer donor (ETDPP-2P) and a non-fullerene acceptor IT-M leads to a visible-near-infrared photoresponse in all small molecule organic solar cells with a power conversion efficiency of 5.69%.

Materials design strategies for high open circuit voltage organic photovoltaics.

In the organic photovoltaic community, extensive efforts have been made in proposing resolutions for depressing V_oc loss related to the molecular structures and optoelectronic properties of materials in bulk heterojunctions.

Perylene monoimide based non-fullerene acceptors with fluorene, silafluorene and carbazole as linkers were synthesized and compared regarding their structural, optical, electronic and photovoltaic properties.

Introducing a medium bandgap electron acceptor into the PTB7-Th:COi8DFIC solar cell increases both thermal stability and PCE without external treatments.

The photovoltaic properties of near-infrared non-fullerene acceptors are improved by isomerizing the linkage positions of thieno[3,4-b]thiophene.

Side chain engineering of fused bithiophene imide oligomers yields a new series of random copolymers with tunable polymer chain packing and film morphology. When applied in all-polymer solar cells, an 8.32% efficiency is obtained.

Efficient non-fullerene polymer solar cells based on P2F-EHp and ITIC derivatives were achieved by blade-coating under the ambient air conditions.

In this work, two novel two-dimensional (2D) benzo[1,2-b:4,5-b′]difuran (BDF)-based wide bandgap polymers were designed using a halogenation strategy by incorporating fluorine- and chlorine-substituted conjugated side chains, respectively.

An A–D–D–A-type near-infrared non-fullerene small-molecule acceptor IDT2-DFIC with indacenodithiophene–indacenodithiophene (IDT2) as donating core and 2-(5,6-difluoro-3-oxo-2,3-dihydro-1H-inden-1-ylidene)malononitrile (2FIC) as electron withdrawing end groups has been synthesized.

The molecular backbone design and sidechain control are both considered for fused-ring electron acceptors to fine-tune the morphology and miscibility of the active layers for organic solar cells.

Our results suggest the conditions to promote an efficient hole transfer from acceptors induced by molecular orbital delocalization.

Incorporating an infrared nonfullerene acceptor O6T-4F enhances the exciton utilization and extends the absorption, leading to an increased PCE of organic solar cells.

Fullerene-free organic solar cells (OSCs) were fabricated using a blend of wide bandgap donor PBDB-T and ultranarrow bandgap acceptor IEICO-4F as binary photoactive layers.

Identifying the best ratios of components in ternary blend polymer solar cell could lead to more photostable organic solar cells.

Fullerene and fullerene-free organic photovoltaics.

A series of conjugated terpolymers bearing weak and strong accepting units were synthesized. Their optical and electrochemical properties and device performance can be easily tuned by controlling molar ratio of two accepting units.

Based on comparisons of two all-polymer solar cells based on PTzBI:N2200 and PNDN-T:N2200 blends, factors limiting the device characteristics are investigated.

Fullerene-free polymer solar cells with the as-cast blend film of IDT-3MT and PBDB-T exhibited a high PCE of 8.40%.

We have systematically investigated the synergistic effect of thermal annealing and interlayer modification on improving the performance of inverted non-fullerene organic solar cells.