Fluorinated n-type conjugated polymers are used as efficient electron acceptor to demonstrate high-performance all-polymer solar cells. The exciton generation, dissociation, and charge-transporting properties of blend films are improved by using these fluorinated n-type polymers to result in enhanced photocurrent and suppressed charge recombination.

Low-temperature, solution-processable Cu-doped NiOX (Cu:NiOx ), prepared via combustion chemistry, is demonstrated as an excellent hole-transporting layer (HTL) for thin-film perovskite solar cells (PVSCs). Its good crystallinity, conductivity, and hole-extraction properties enable the derived PVSC to have a high power conversion efficiency (PCE) of 17.74%. Its general applicability for various elecrode materials is also revealed.

We review the morphologies of polymer-based solar cells and the parameters that govern the evolution of the morphologies and describe different approaches to achieve the optimum morphology for a BHJ OPV. While there are some distinct differences, there are also some commonalities. It is evident that morphology and the control of the morphology are important for device performance and, by controlling the thermodynamics, in particular, the interactions of the components, and by controlling kinetic parameters, like the rate of solvent evaporation, crystallization and phase separation, optimized morphologies for a given system can be achieved. While much research has focused on P3HT, it is evident that a clearer understanding of the morphology and the evolution of the morphology in low bad gap polymer systems will increase the efficiency further. While current OPVs are on the verge of breaking the 10% barrier, manipulating and controlling the morphology will still be key for device optimization and, equally important, for the fabrication of these devices in an industrial setting.

Copolymers composed of diketopyrrolopyrrole and phenylene units with different numbers of fluorine subsitution are synthesized. When the effect of the number of fluorine substitution on the n-channel transporting property is investigated, the polymer with four fluorine substitutions exhibits the best n-type charge-transporting behavior with an electron mobility of 2.36 cm(2) V(-1) s(1).

PC 61 BM)/cathode, in which the PEDOT:PSS and PC 61 BM function as hole-transporting layer (HTL) and electron-transporting layer (ETL), respectively, for effi cient charge extraction. Recent progress in optimizing perovskite morphology (e.g., crystallinity or surface coverage) by solvent-engineering technique has resulted in high PCE of >14% in the PEDOT:PSS-based PHJ PVSC with high short-circuit current density ( J SC ) and fi ll factor ( FF ). However, the open-circuit voltage ( V OC ) (0.90−0.95 V) is still much lower than that (≈1.05 V) obtained from mesosuperstructured PVSC. This is a major obstacle for further improving the performance of PVSC. [ 6 ] Although the origin of such limited V OC for PHJ PVSC is not clear, it might arise from the mismatched energy levels between the valence band of CH 3 NH 3 PbI 3 (−5.4 eV) and the work function of PEDOT:PSS (−5.0 eV) ( Scheme 1 ).Because the V OC of a PHJ PVSC is directly infl uenced by the interfaces between perovskites and employed charge-transporting interlayers, the potential energy loss at the interface between PEDOT:PSS and CH 3 NH 3 PbI 3 may restrain the built-in potential in PHJ PVSCs leading to decreased V OC . [ 7 ] Therefore, various inorganic-based HTLs with high work function (WF) (or deep valence band), especially transition metal oxides (TMOs), have been introduced recently in PHJ PVSCs to create better matched energy with the valence band of CH 3 NH 3 PbI 3 in device for achieving higher V OC and device performance. [ 8 ] However, these TMO-based HTLs encounter severe surface charge recombination because their low hole mobility or surface defects (dangling bonds) exist in the metal oxide. [ 9 ] Moreover, the high-temperature sintering process (>300 °C) for achieving high-crystallinity TMO thin fi lms may impede the R-2-R printing process. [ 10 ] In this regard, development of low-temperature processible inorganic HTL with high hole mobility is highly desirable for improving the performance of PHJ PVSCs.Besides TMOs, copper thiocyanate (CuSCN) is another attractive candidate as effi cient HTL for PHJ PVSCs. Previously, CuSCN has been demonstrated as an intrinsic p-type semiconductor with high hole mobility (≈0.1 cm 2 V −1 s −1 ) due to the associated copper defi ciency in its composition. [ 11 ] Moreover, CuSCN possesses adequate energy levels ( E VB = −5.4 eV and E CB = −1.8 eV) which allow it to function as an excellent HTL. In addition, the wide band-gap ( E g = 3.6 eV) CuSCN provides superior transparency across the UV-vis-NIR spectrum, which facilitates photoactive materials to absorb more light for generating higher photocurrent in solar cells. Inspired by these unique features, CuSCN has been used as HTL in organic solar cells and light-emitting diodes. [ 12 ] Adv. Energy Mater. 2015, 5, 1500486 www.MaterialsViews.com www.advenergymat.de Adv. Energy Mater. 2015, 5, 1500486 www.MaterialsViews.com www.advenergymat.de Figure 5. a) UV-vis transmittance of the semitransparent PVSC devices with different thicknesses of perovskite layer (inset ...