The straightforward palladium-catalyzed synthesis protocol toward spiro-fused perylene diimides is developed. The reaction involves two palladium-catalyzed C–H activations and 4-fold C–C bond formation sequence from readily available precursors. This facile and step-economic approach also provides another convenient access to ethylene-bridged dimer (NDP) and further π-extended spiro system (SNTP). In addition, the molecular structure of spirodiperylenetetraimide (SDP) is illustrated to show a three-dimensional (3D) cruciform configuration, and its absorbance is distinctly red-shifted due to the significant spiroconjugation effect. With combined properties of broadened and intensive absorption, aligned LUMO levels, and unique molecular geometry, the spiro-fused PDI system represents a new kind of high-performance semiconducting framework as the electron acceptor in high-efficiency organic solar cells.

The first example of sila-annulation onto the perylene diimide core that allows the effective and practical synthesis of both sila- and disilaperylene diimides (Si-PDIs and 2Si-PDIs) in one pot through palladium-catalyzed Si–C bond formation is presented. The corresponding sila-annulated perylene diimides demonstrated exceptional optical properties with noteworthy bathochromic shifts and excellent fluorescence quantum yields. Single crystal analysis revealed almost planar molecular structures and distinct packing arrangements with intense π–π interactions. Their single crystal OFET devices showed good electron mobilities of up to 0.3 cm2 V–1 s–1 under a nitrogen atmosphere.

Two twisted singly linked perylene bisimide (PBI) dimers with chalcogen bridges in the PBI cores, named C4,4-SdiPBI-S and C4,4-SdiPBI-Se, were synthesized as acceptors for nonfullerene all-small-molecule organic solar cells (NF all-SMSCs). A moderate-band-gap small-molecule DR3TBDTT used as the electron donor displayed complementary absorption with C4,4-SdiPBI-S and C4,4-SdiPBI-Se. It was found that solvent-vapor annealing (SVA) played a critical role in the photovoltaic performance in NF all-SMSCs, which improves the crystallinity of the donor and acceptors, promotes the proper phase segregation domain size, and therefore enhances charge transport. The power conversion efficiencies (PCEs) of NF all-SMSC devices based on DR3TBDTT/C4,4-SdiPBI-S and DR3TBDTT/C4,4-SdiPBI-Se increased from 2.52% to 5.81% (JSC = 11.12 mA cm–2, VOC = 0.91 V, and FF = 57.32%) and from 2.65% to 6.22% (JSC = 11.55 mA cm–2, VOC = 0.92 V, and FF = 58.72%), respectively, after exposure to chloroform vapor. The best efficiency of 6.22% is one of the highest PCEs for NF all-SMSC-based PBI acceptors so far. The studies illustrate that highly efficient NF all-SMSCs can be achieved by using a PBI acceptor with a suitable SVA process.Keywords: nonfullerene acceptor; nonfullerene all-small-molecule organic solar cells; perylene bisimide; solvent-vapor annealing; twisted conformation;

During the past two years, non-fullerene electron acceptors for organic solar cells have attracted considerable attention. Significant progress has been made in that the power conversion efficiency of polymer solar cells based on non-fullerene small molecule acceptors now exceeds 12%, exhibiting many advantages over their fullerene counterparts. One of the greatest strengths for NFAs is their tunability via chemical modulation to fine-tune their absorption, energy level and electronic mobility, which is difficult to achieve with fullerene derivatives. This review describes very recent developments of polymer donor:small molecular non-fullerene acceptors in several systems since 2015, including rylene imide, indacenodithiophene and diketopyrrolopyrrole-based small molecular acceptors. Molecular design considerations and structure–property relationships are also discussed.

Two twisted terrylene diimides (TDIs), namely TDI2 and BTDI3, have been designed and synthesized. In comparison to monomeric TDI, their molecular geometries and optoelectronic properties have been systematically investigated. BTDI3, with a highly twisted 3D geometry, shows the best light-absorbing capability in the range of 500–700 nm and a suitable LUMO level. Simultaneously, a preliminary exploration of their photovoltaic performances was carried out. The optimized device based on PBDT-TS1/BTDI3 produces a power conversion efficiency (PCE) of 3.64%, demonstrating the potential of terrylene dyes in the photovoltaics field.

A series of acceptor–donor–acceptor (A–D–A) conjugated molecules based on naphthalene diimide dimers bridged with different π-conjugated heterocyclic units (NDI–π–NDI) have been designed and synthesized. By an ingenious design strategy, the LUMO (the lowest unoccupied molecular orbital) of the NDI-based small molecules is well controlled to a relatively constant value of −3.8 to −3.9 eV, whereas their HOMO (the highest occupied molecular orbital) could be tuned over a wide range, from −6.5 eV (compound 1) to −5.5 eV (compound 5), leading to varied band gaps from 2.6 eV to 1.5 eV. Organic field-effect transistor (OFET) characterization of these NDI–π–NDI molecules shows that compounds 1, 2, and 3 have good n-type semiconducting properties in a N2 atmosphere with the maximum electron mobilities up to 0.15 cm2 V−1 s−1, 0.46 cm2 V−1 s−1 and 0.57 cm2 V−1 s−1, respectively. Compounds 4 and 5, due to the high-lying HOMO levels and reduced energy band gaps, have ambipolar semiconducting properties and OFETs based on 5 show the highest electron and hole mobilities up to 1.23 cm2 V−1 s−1 and 0.0074 cm2 V−1 s−1, respectively. Moreover, the performances are enhanced under thermal treatment because of the increased crystallinity as evidenced by X-ray diffraction (XRD) and atomic force microscopy (AFM). The easily tunable electronic energy levels make the NDI-based semiconductors promising n-channel and ambipolar components in organic devices.

Simple methods for patterning single crystals are critical to fully realize their applications in electronics. However, traditional vapor and solution methods are deficient in terms of crystals with random spatial and quality distributions. In this work, we report a dewetting-induced assembly strategy for obtaining large-scale and highly oriented organic crystal arrays. We also demonstrate that organic field-effect transistors (OFETs) fabricated from patterned n-alkyl-substituted tetrachloroperylene diimide (R–4ClPDI) single crystals can reach a maximum mobility of 0.65 cm2 V–1 s–1 for C8–4ClPDI in ambient conditions. This technique constitutes a facile method for fabricating OFETs with high performances for large-scale electronics applications.

In this paper, we designed, synthesized, and characterized a set of non-fullerene small molecules based on bis(perylene diimide) with DACH bridge. Theoretical calculations make clear that the introduction of the DACH bridge into PPDI forms a U-shape framework, with pi–pi interactions between PDIs. We investigate the performances of non-fullerene solar cells comprising racemic and enantiomerically pure DACH-PPDIs as the electron acceptor and PTB7-Th as the electron donor. As a consequence, a power conversion efficiency (PCE) of 4.68% is achieved with inverted device architecture. Furthermore, the device behaviour, morphological feature and charge transport properties were also investigated. It is a potential way to design highly efficient non-fullerene organic solar cell by tuning the structure of PDI to reach highly efficient photovoltaic performances.

Four novel metal-free D–A–π–A organic sensitizers (ND01–ND04) based on N-annulated perylene (NP) derivatives as efficient electron donors for dye-sensitized solar cells (DSSCs) are designed. Among them, ND02 featuring bulky 4-methoxyphenyl as the additional electron-donating substituents on the NP unit shows a power conversion efficiency as high as 8.30%.

Molecular packing motifs in solid states is the dominant factor affecting the n-channel organic field-effect transistors (OFETs). However, few systematic researches were performed in the different extensions of π-conjugated molecules with the uniform substitution effecting the molecular packing motifs. In this manuscript, OFET devices based on three latterally expanded rylene diimides end-functionalized with uniform 3-hexylundecyl substitution on the imide positions were systematically studied on the relationship of molecular stacking, film microstructure, and charge transport. As the π-conjugated systems expanded from doubly linked perylene diimide dimer (d-4CldiPDI, 1), triply linked perylene diimide dimer (t-4CldiPDI, 2), to hybrid array (NDI-PDI-NDI, 3), their corresponding molecular packing motifs exhibited a divide: the optimized molecular configuration became more planar and d (001) spacing distances became larger, which resulted in a larger π–π overlapping. Thus, an enhanced electron mobility was obtained. A typical n-channel field-effect characteristic was observed in thin film devices based on these molecules under ambient conditions. Especially, the hybrid system (3) with more planar and π-expanded aromatic backbone exhibited superior electron mobility approaching 0.44 cm2 V–1 s–1 and on/off ratio of 106 after optimal annealing in this study.Keywords: d-spacings; lateral expansion; molecular packing motifs; n-channel OFETs; rylene diimides; uniform branched side chains

A series of nonbay region cyano-substituted tetrachloroperylene diimides with tunable LUMO energy levels from −4.21 to −4.64 eV were developed. The excellent linear correlation between LUMO energy levels and the number of cyano groups indicated that the LUMO energy levels could be lowered effectively and predictably by incorporating cyano groups.

A new family of perpendicularly entangled perylene diimides and di(perylene diimide) dimers featuring double linkage was synthesized via copper-mediated Ullmann coupling. The highly twisting structures endow them remarkable electron transport characteristics with comparable mobility reaching 0.16 cm2 V−1 s−1 and an on/off current ratio up to 5.0 × 106 in air for PDI dimer based solution-processed OTFTs. While diPDI dimers with expanded conjugated core proved their competing electron mobilities as PDI dimers, especially for their low threshold voltage and good air stability.

We present here a new family of hybrid rylene arrays (3a–d) by the combination of Stille coupling and C–H transformation via a facile one-pot synthesis. The π-expanded rylene diimides exhibit broadened and intensive optical absorption accompanied by higher electron affinity. The linear alkyl chain substituted NDI-diPDI-NDI (3b) revealed its electron transporting characteristics with good air stability and low threshold voltage.

We present here the synthesis, characterization, and thin film transistor performance of six semiconducting materials by alkyl substitution on the N-positions of tetrachlorinated di(perylene bisimide) (4CldiPBI). Although the different alkyl chain substituents have a negligible effect on the absorption maximum and energy gap, the DSC thermal behaviour and electron performance are sensitive to the length of the alkyl chains. Substitution with the longer alkyl chains produced higher electron mobilities in air. C18-4CldiPBI (6), which exhibited the best solubility in common organic solvents, has demonstrated excellent thin film electron performance in air with the mobility as high as 0.70 cm2 V−1 s−1 and a high on/off ratio of 4 × 107. Furthermore, the device performance showed good stability in air for months without apparent degradation.

•D-A polymers bearing perylene esters (PTACs) and thiophene derivatives were designed and synthesized.•Their structures and photophysical properties were unambiguously investigated by spectroscopy.•All-polymer solar cells based on these polymers as acceptor and P3HT as donor were fabricated.•A maximum PCE of 1.1% with VOC as high as 0.92 V based on these devices have been achieved.Four D-A polymers alternated between 3,4,9,10-tetra(n-alkoxy-carbonyl)-perylenes (PTACs) and thiophene derivatives (TT and BDT) in backbones were synthesized under Stille coupling conditions. Their structures were unambiguously verified by 1H NMR and elemental analysis. These polymers showed high-lying LUMO energy levels of about −3.50 eV due to the less electron deficient characteristics of PTACs units. All-polymer solar cells based on these PTAC-based polymers as acceptor and P3HT as donor have been fabricated. With annealing at 100 °C for 15 min, P4/P3HT blends demonstrated a power conversion efficiency of up to 1.10% with a short circuit current (JSC) of 2.9 mA/cm2, an open circuit voltage (VOC) 0.92 V, and a fill factor (FF) of 0.40, illustrating that PTACs are attractive candidates for solar cells.

A new family of perpendicularly entangled perylene diimides and di(perylene diimide) dimers featuring double linkage was synthesized via copper-mediated Ullmann coupling. The highly twisting structures endow them remarkable electron transport characteristics with comparable mobility reaching 0.16 cm2 V−1 s−1 and an on/off current ratio up to 5.0 × 106 in air for PDI dimer based solution-processed OTFTs. While diPDI dimers with expanded conjugated core proved their competing electron mobilities as PDI dimers, especially for their low threshold voltage and good air stability.

During the past two years, non-fullerene electron acceptors for organic solar cells have attracted considerable attention. Significant progress has been made in that the power conversion efficiency of polymer solar cells based on non-fullerene small molecule acceptors now exceeds 12%, exhibiting many advantages over their fullerene counterparts. One of the greatest strengths for NFAs is their tunability via chemical modulation to fine-tune their absorption, energy level and electronic mobility, which is difficult to achieve with fullerene derivatives. This review describes very recent developments of polymer donor:small molecular non-fullerene acceptors in several systems since 2015, including rylene imide, indacenodithiophene and diketopyrrolopyrrole-based small molecular acceptors. Molecular design considerations and structure–property relationships are also discussed.

We present here a new family of hybrid rylene arrays (3a–d) by the combination of Stille coupling and C–H transformation via a facile one-pot synthesis. The π-expanded rylene diimides exhibit broadened and intensive optical absorption accompanied by higher electron affinity. The linear alkyl chain substituted NDI-diPDI-NDI (3b) revealed its electron transporting characteristics with good air stability and low threshold voltage.

We present here the synthesis, characterization, and thin film transistor performance of six semiconducting materials by alkyl substitution on the N-positions of tetrachlorinated di(perylene bisimide) (4CldiPBI). Although the different alkyl chain substituents have a negligible effect on the absorption maximum and energy gap, the DSC thermal behaviour and electron performance are sensitive to the length of the alkyl chains. Substitution with the longer alkyl chains produced higher electron mobilities in air. C18-4CldiPBI (6), which exhibited the best solubility in common organic solvents, has demonstrated excellent thin film electron performance in air with the mobility as high as 0.70 cm2 V−1 s−1 and a high on/off ratio of 4 × 107. Furthermore, the device performance showed good stability in air for months without apparent degradation.

A series of acceptor–donor–acceptor (A–D–A) conjugated molecules based on naphthalene diimide dimers bridged with different π-conjugated heterocyclic units (NDI–π–NDI) have been designed and synthesized. By an ingenious design strategy, the LUMO (the lowest unoccupied molecular orbital) of the NDI-based small molecules is well controlled to a relatively constant value of −3.8 to −3.9 eV, whereas their HOMO (the highest occupied molecular orbital) could be tuned over a wide range, from −6.5 eV (compound 1) to −5.5 eV (compound 5), leading to varied band gaps from 2.6 eV to 1.5 eV. Organic field-effect transistor (OFET) characterization of these NDI–π–NDI molecules shows that compounds 1, 2, and 3 have good n-type semiconducting properties in a N2 atmosphere with the maximum electron mobilities up to 0.15 cm2 V−1 s−1, 0.46 cm2 V−1 s−1 and 0.57 cm2 V−1 s−1, respectively. Compounds 4 and 5, due to the high-lying HOMO levels and reduced energy band gaps, have ambipolar semiconducting properties and OFETs based on 5 show the highest electron and hole mobilities up to 1.23 cm2 V−1 s−1 and 0.0074 cm2 V−1 s−1, respectively. Moreover, the performances are enhanced under thermal treatment because of the increased crystallinity as evidenced by X-ray diffraction (XRD) and atomic force microscopy (AFM). The easily tunable electronic energy levels make the NDI-based semiconductors promising n-channel and ambipolar components in organic devices.

Four novel metal-free D–A–π–A organic sensitizers (ND01–ND04) based on N-annulated perylene (NP) derivatives as efficient electron donors for dye-sensitized solar cells (DSSCs) are designed. Among them, ND02 featuring bulky 4-methoxyphenyl as the additional electron-donating substituents on the NP unit shows a power conversion efficiency as high as 8.30%.