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This paper successfully demonstrates that solution‐processable cesium carbonate (Cs2CO3) and photoannealing treatments can be used to replace thermal annealing treatments. The power conversion efficiency (PCE) is quite low in the initial stage, while the PCE dramatically increases following continuous light illumination and reaches a saturated state after 15 min of light illumination. Raman spectra and X‐ray photoelectron spectroscopy (XPS) are then used to show that the Cs2CO3 molecule decomposes and transforms into a mixture of cesium oxide (CsOX), which is the major constituent of cesium oxide (Cs2O), and small amounts of cesium dioxide (Cs2O2) and cesium oxide (CsO2). In addition, following the spin coating of a fresh Cs2CO3 solution onto the indium tin oxide surface and 15 min of photoannealing, polymer solar cells show improved photovoltaic performance compared with the use of thermally annealed Cs2CO3 and ZnO films as the electron extraction layer. [ABSTRACT FROM AUTHOR]

• NC 70 BA plays a dominant role in the photocurrent generating and charge transport. • The separation of exciton of NCBDT-4Cl mainly occurs on the NCBDT-4Cl/NC 70 BA interface. • The OSCs based on NC 70 BA exhibit a significant increase of 10% in PCE. • The shallower energy levels and better compatibility for double side chain fullerene derivative NC 70 BA than single side chain fullerene PC 71 BM. In this study, ternary organic solar cells (OSCs) are fabricated with the PBDB-T-2F as a polymer donor and NCBDT-4Cl as a fullerene-free acceptor, double side chain fullerene derivative NC 70 BA as a third component material and single side chain fullerene PC 71 BM as reference third component materials. The NC 70 BA-based ternary OSCs exhibit the highest PCE of 13.82%, which is 10% higher than that of PBDB-T-2F:NCBDT-4Cl binary OSCs and slightly higher than PC 71 BM-based ternary OSCs (13.24%). Detailed studies suggest that the shallow LUMO levels and double side chain for NC 70 BA is beneficial to broaden energy bandgap and improve compatibility, which is enhancing J SC and FF value. This work suggests that double side chain fullerene derivative NC 70 BA as third component materials is a promising way to finely tune the detailed photovoltaic parameters and further improve the photovoltaic performance of OSCs. [ABSTRACT FROM AUTHOR]

• PEIE/TiO X bilayer films were produced by spin-coating the blend solution of PEIE and TiO X. • PEIE/TiO X showed better chemical stability and charge carrier transport ability. • PEIE/TiO X could replace Ca or TiO X as the EEL in PSCs devices. One of the challenges facing the fabrication of high-performance conventional structure polymer solar cells (PSCs) is the development of new interface materials that have better air stability and charge carrier collection and transport ability. In this study, the mixture thin films of polyethylenimine ethoxylated (PEIE) and TiO X are developed as the electron extraction layer (EEL) and Ag as the cathode for the application in PSCs, replacing the Ca/Al composite cathode. Ultraviolet photoelectron spectroscopy (UPS) and space-charge-limited current (SCLC) measurements demonstrate that PEIE:TiO X /Ag shows appropriate energy levels, substantially reduced barrier potential, weakened charge carrier recombination and enhanced electron mobility. As a result, the PEIE:TiO X -based PSCs demonstrate not only an enhanced power conversion efficiency (PCE) of 10.94% but also the photovoltaic performance insensitive to the storage time, yielding an aged PCE that is 92% of the fresh PCE. This result can be further explained by the dependence of the charge carrier mobility on storage time. Our work suggests exploiting the PEIE:TiO X /Ag composite thin films as the composite cathode replacing Ca/Al thin films for successfully enhancing the photovoltaic performance and improving the stability of PSCs. [ABSTRACT FROM AUTHOR]

Abstract Ternary organic solar cells (OSCs) are fabricate using a single wide-bandgap poly[(2,6-(4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)-benzo[1,2-b:4,5-b0]dithiophene))-alt-(5,5-(10,30-di-2-thienyl-50,70-bis(2-ethylhexyl)benzo[10,20-c:40,50-c0]dithiophene-4,8-dione))] (PBDB-T) as the donor material and 3,9-bis (2-methylene-(3-(1,1-dicyanomethylene)-indanone)-5,5,11,11-tetrakis (4-hexylphenyl)-dithieno[2,3-d:2′, 3′-d′]-s-indaceno[1,2-b:5,6-b']dithiophene) (ITIC) as the acceptor and poly[[N,N′-bis(2-octyldodecyl)-naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-(3,3′-difluoro-2,2′-bithiophene)-5,5′-diyl] (F N2200) as third component materials. Due to the strong absorption ability at the short-wavelength region. The best power conversion efficiency (PCE) of 10.9% is achieve for the OSCs via incorporating 10 wt% F N2200 in blend-acceptor materials, with an enhance the short-circuit current (J SC) of 17.6 mA cm−2, fill factor (FF) of 68.0% and stable open-circuit voltage (V OC) of 0.91 V relative to binary OSCs. The short-wavelength absorption windows of F N2200 is favourable the harvesting of as many as possible photons and the enhance exciton dissociation ratio at the ITIC/F N2200 interface due to the deeper LUMO energy level of F N2200 relative to ITIC molecule. Meanwhile, the incorporation small amount of F N2200 is weaken monomolecular recombination and bimolecular recombination under open-circuit and short-circuit conditions respectively and enhance the charge carrier mobility. The use of PBDB-T as donor and the blend of ITIC and F N2200 as an electron acceptor provides a useful strategy for exploring high-performance ternary OSCs. Highlights • Ternary OSCs were fabricated with F N2200 as third component materials. • The ternary photoactive layer is weaken charge carrier recombination. • The improvement of exciton-dissociation at the PBDB-T/acceptor interface. • The enhanced photovoltaic performance, especially under weak light intensity. [ABSTRACT FROM AUTHOR]

A dihydronaphthyl-based C60 bisadduct (NCBA) acceptor is introduce as a third component to typical PTB7: PC 71 BM binary polymer solar cells (PSCs). NCBA play bridging role between the lowest unoccupied molecular orbital (LUMO) of PTB7 and PC 71 BM and provides more routes for charge carrier transfer at the interface between PTB7 and PC 71 BM, a higher open-circuit voltage ( V OC ) realize upon addition of NCBA can be achieve relative to the neat PC 71 BM as an electron acceptor. The strong visible light absorption in the range from 350 to 700 nm of NCBA molecule compared with PC 71 BM molecule, it has the effect of apparently complementary visible light absorption compare with the binary PTB7:PC 71 BM thin films. The current density–voltage ( J - V ) characteristics dependent on incident light intensity were employed and to analyze the effect of NCBA concentration on the charge carrier recombination process of ternary PSCs. The crystallinity and surface morphology of the ternary PTB7:NCBA:PC 71 BM thin films with NCBA concentration is 15% of blend acceptor is similar to that of the binary PTB7:PC 71 BM thin films, which guarantees suitable efficient exciton dissociation and charge carrier transport. The transient photovoltage (TPV) and transient photocurrent (TPC) were measured, and the results illustrate the effect of NCBA as the third component materials in terms of higher charge carrier density and long charge carrier lifetime and weaken charge carrier recombination. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ternary PSCs were fabricated with PBDB-TF as third component materials. • The improvement of charge dynamics process of ternary photoactive layer by ternary strategy. • The improved exciton-dissociation at the donor–blend acceptor interface. In this manuscripts, a ternary polymer solar cells (PSCs) are fabricate with two "D18-series" donor (D18-Cl and D18) as blend donor and T6 as acceptor. The effects of D18-Cl and D18 in ternary PSC on the film morphology, photoelectronic properties and charge carrier dynamics were systematically investigated. By finely adjusting the D18 content, a power conversion efficiency (PCE) of 16.66 % is achieved in the optimized ternary PSCs with 35 wt% D18 in donor, resulting from significantly improved short-circuit-current density (J SC) of 26.80 mA cm−2 in comparison with those of D18-Cl:Y6 binary PSCs. The J SC of ternary PSCs monotonously increase along with the incorporation of D18, indicating that D18 is comprehensively optimal short wavelength photon harvesting compared with D18-Cl. Both D18-Cl and D18 are shown similar highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels, which is beneficial to efficient charge transport at the blend donor domain. Our work indicates that the blend of D18-Cl and D18 as blend donor and Y6 as electron acceptor to boost photovoltaic performance in the ternary PSCs. [ABSTRACT FROM AUTHOR]

Photo-annealing treatment has successfully been demonstrated in organic solar cells (OSCs) with solution-processable titanium (diisopropoxide) bis(2,4-pentanedionate) (TIPD) as an electron extraction layer; this process was shown without thermal annealing treatment. The power conversion efficiency (PCE) is quite low in the initial stage, though it dramatically increases following constant light illumination and reaches a saturated state after 9 min of light illumination. X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) and ultraviolet photoemission spectroscopy (UPS) were used, and they showed that the TIPD molecules decomposed and formed stable Ti O bonds. According to photocurrent density-effective voltage curve (J ph - V eff), short-circuit current density (J SC) and open-circuit voltage (V OC) value under different light intensity, the photo-annealed TIPD-based OSCs showed efficient charge transport and suppressed charge recombination. Thus, after a fresh TIPD solution was spin-coated onto the indium tin oxide (ITO) surface and photo-annealed for 9 min, the OSCs showed the highest photovoltaic performance compared to ZnO-based OSCs. [Display omitted] [ABSTRACT FROM AUTHOR]

In this study, a ternary polymer solar cell (PSCs) are fabricated by using two well-compatible donors as a blend donor (D18 as the host donor and PBDB-TF as the guest donor) and Y6 as an acceptor. The D18:Y6 and PBDB-TF:Y6 binary PSCs exhibit 13.96% and 13.42% power conversion efficiencies (PCEs), respectively. D18 and PBDB-TF have similar highest occupied molecular orbital (HOMO) energy levels, which prevents the formation of charge recombination centers within photoactive layer. The increased short-circuit current density (J SC) is mainly attributed to the complementary absorption spectra of PBDB-TF to that of D18 and Y6. In addition, the cascade lowest unoccupied molecular orbital (LUMO) energy levels of D18 and PBDB-TF lead to improved exciton dissociation and charge transport at the D18/PBDB-TF interface. The optimized ternary PSCs show highest PCE of 14.85%. Such ternary strategy with two well-compatible donors with similar HOMO energy levels and cascade LUMO energy levels is an efficient method to realize performance improvement of PSCs. [Display omitted] • Ternary PSCs were fabricated with PBDB-TF as third component materials. • The improvement of charge dynamics process by ternary strategy. • The improved exciton-dissociation at the donor–blend acceptor interface. • The ternary PSCs with blend donor achieved a PCE of 14.85%. [ABSTRACT FROM AUTHOR]

The ternary organic solar cells (OSCs) were fabricated with PBDB-T as donor and a blend of IEICO-4F and NC 70 BA as the acceptor and the power conversion efficiency (PCE) reaches 10.92%. Due to good compatibility and cascade LUMO level among PBDB-T, a large amount of IEICO-4F and a small amount of NC 70 BA (the ratio of IEICO-4F:NC 70 BA is 85:15), which beneficial for adjusting lowest unoccupied molecular orbital (LUMO) levels of blend acceptor and wide energy offset between the donor and acceptor materials, leading to the enhancement of the open-circuit voltage (V OC). The optimized ternary PBDB-T:IEICO-4F:NC 70 BA films is more efficient exciton dissociation and suppress charge carrier recombination than that of binary PBDB-T:IEICO-4F and PBDB-T:NC 70 BA films, leading to small energy losses. In addition, this approach maintains PCE without sacrificing short-circuit current density (J SC) and fill factor (FF), even if the weak long and near-infrared wavelength photon harvesting. A more than 10% PCE improvement is achieve by employing a ternary strategy in comparison to PBDB-T:IEICO-4F-based binary OSCs with a PCE of 9.87%. Simultaneously, the optimized ternary PBDB-T:IEICO-4F:NC 70 BA OSCs exhibit the excellent thermal stability and 78.8% initial PCE under thermal annealing treatment at 80 °C for 20 h. • The ternary OSCs with blend acceptor achieved a PCE of 10.92%. • Around 10% PCE improvement is obtained by employing ternary strategy. • The improvement of exciton-dissociation at the Donor/blend acceptor interface. • The simultaneously enhance performance and stability for ternary OSCs. [ABSTRACT FROM AUTHOR]

Ternary polymer solar cells (PSCs) are fabricated that consisted of a blend of IEICO‐4F and 3TT‐FIC as electron acceptors and PBDB‐T as an electron donor. The power conversion efficiency (PCE) of ternary PSCs is increased from 9.9% to 11.22% via the blend of IEICO‐4F and 3TT‐FIC as electron acceptors (the ratio of IEICO‐4F:3TT‐FIC is 6:4), which enhances the open‐circuit voltage (VOC) from 0.71 to 0.78 V. The main contribution of the blended acceptor is its broad energy level offset between the donor and acceptor (from 1.26 to 1.30 eV) due to the enhanced lowest unoccupied molecular orbital energy levels of the blended acceptor. Meanwhile, the small energy losses of the ternary photoactive layer (reduced from 0.55 to 0.52 eV) are simultaneously due to the more efficient exciton dissociation and the suppressed charge carrier recombination. This work provides an effective strategy for improving the photovoltaic performance of binary PSCs. [ABSTRACT FROM AUTHOR]