Conjugated polymer/Si hybrid solar cells are fabricated based on a Si nanowire array (SiNW) substrate prepared by metal-assisted electroless etching. With a facile method involving immersing the SiNW substrate in anisotropic tetramethylammonium hydroxide (TMAH) solution just for few minutes, the power conversation efficiency (PCE) of the hybrid solar cell can be 12.36%, which is 69.5% higher than that of pristine one. The efficiency improvement mechanism is discussed and analyzed in detail, and all the results demonstrate that with the TMAH treatment, the density of the SiNWs is reduced, and the electrochemical contact between the PEDOT:PSS and SiNWs as well as the rear contact is obviously improved, all of which significantly suppress the charge recombination in the hybrid solar cells. Our major investigation emphasizes the importance of the TMAH treatment to nanostructured Si and renders a promising approach to obtain low-cost and high performance conjugated polymer/Si hybrid solar cells.

•Silicon microhole arrays/ionic liquids junction is constructed for solar cells.•Large holes make better electrochemical contact between electrolytes and SiMHs.•Ionic liquids offer SiNWs cells better long-term stability than reference ones.Silicon microhole arrays (SiMHs) structure is constructed and fabricated by a low-cost maskless anodic etching process, which is applied as the photoanode for the silicon photoelectrochemical (PEC) cells. The depths of silicon microhole arrays can be independently controlled by the etching time. The light-scattering properties are also investigated. Additionally, surface morphology analysis show that large hole diameters of SiMHs is very favourable for the full-filling of ionic liquids electrolyte. Therefore, better electrochemical contact as well as high ionic conductivity of the ionic liquids electrolyte renders the PEC SiMHs solar cells to exhibit more excellent performance. After optimization, the maximum PCE could be achieved at 4.04% for the SiMHs cell. The performance of the SiMHs cell is highly comparable to that of silicon nanowires cell. More importantly, the liquid-state electrolyte is confined in the unique microhole structure, which can obviously prevent the leakage of the ionic liquids electrolyte, resulting in much better long-term stability than the reference devices. These preliminary results validate the concept of interpenetrating networks with semiconductor structure/ILs junction to develop stable and efficient PEC cells.

A light-scattering cyanobiphenyl derivative 6-[(4'-cyano(1,1'-biphenyl)-4-yl)oxy]he-xanoic acid (CBHA) was designed, synthesized and applied as a co-adsorbent for dye-sensitized solar cells. The effect of CBHA on the light absorption and reflectance of dyed-TiO2 photoanodes was investigated in detailed. It revealed that a certain amount of CBHA adding to dye Z907 could obviously increase the light absorption of TiO2 photoanodes by decreasing the dye loading amount and possibility of aggregation. Meanwhile, light-scattering property of CBHA rendered their TiO2 photoanodes higher light-harvesting efficiency. In addition, electrochemical impedance spectroscopy results indicated that CBHA could restrain the interfacial electron recombination for longer life time. Thus, a performance improvement of ∼0.81% from 5.23% to 6.04% could be obtained by the resulting device employing CBHA. Moreover, the DSSCs with CBHA also display better stability than the referenced devices. This novel light-scattering co-absorbent offers us a feasible strategy to design multiple functional co-adsorbents for high performance dye-sensitized solar cells.

Three simple imidazolium-type ionic liquids with benzene cores (abbreviated as [TMImB][Br] and [TMImB][TFSI]) have been successfully designed, synthesized and characterized. The chemical structure, thermal and electrochemical properties have also been investigated in detail. Moreover, it is revealed that adding 20 wt% [TMImB][TFSI] could effectively suppress the crystal growth of the typical ionic conductor 1-ethyl-3-methylimidazolium iodide (EMII). Meanwhile, [TMImB][TFSI] can facilitate the EMII-based solid-state electrolyte to form a much smoother surface morphology than EMII alone, which can improve interfacial electrochemical contact among EMII and porous TiO2 films. Therefore, the resultant solid-state DSSC with [TMImB][TFSI] exhibits a higher efficiency of 5.66% than the DSSC without crystal growth inhibitors, and displays better long-term stability than the DSSC with conventional EMIBF4. These preliminary results provide us with more opportunities to explore new crystal growth inhibitors with special chemical structures for high performance ssDSSCs.

A novel crown ether lithium salt complex [Li∈12-C-4][I] has been designed, synthesized and characterized. The thermal properties of the [Li∈12-C-4][I] based solid-state electrolytes were also investigated in detail. The particular trapping ability of 12-crown-4 to Li+ can obviously reduce the cation–anion (Li+–I−) interaction and hence facilitate favorable electrical properties of the solid-state electrolytes. Therefore, [Li∈12-C-4][I] represents ionic conductivity of 3.93 × 10−5 and 1.53 × 10−4 S cm−1 at 25 and 80 °C, respectively. Further addition of the ionic liquid 1-propyl-3-methylimidazolium iodine as a crystal growth inhibitor can effectively suppress the crystallization of the complex for more amorphous and smoother regions, which are much more conducive towards higher ion conductivity by the segmental motion of molecule chains. For application, the resulting device showed a power conversion efficiency of 5% and displayed excellent long-term stability. These results offer us more opportunities to explore simple and novel solid-state electrolytes for energy storage and conversion.

Carbon nanotubes (CNTs) embedding organic ionic plastic crystals electrolytes were prepared and characterized by thermal analysis and scanning electron microscopy to investigate the influence of CNTs contents on the thermal properties and surface morphology. The investigation showed the addition of CNTs had little effect on the melting points and solid–solid phase transition properties of the plastic crystals electrolytes. However, with CNTs increasing, the solid-state electrolytes produced more defected/amorphous regions, resulting in better ionic conductivity and diffusion coefficients of I− and I3−. Furthermore, based on these solid-state electrolytes, the resulting solid-state dye-sensitized solar cell exhibited maximal power conversion efficiency of 5.60%, and displayed much more excellent long-term stability than that of referenced ionic liquids-based device. These results offer us a feasible method to develop more excellent plastic crystals electrolytes for high performance solid-state dye-sensitized solar cells.

A novel crown ether functionalized ionic liquid has been designed, synthesized and characterized in detail. The thermal properties of the ionic liquid are also investigated. When LiI or MgI2 is introduced into the ionic liquid at the same concentration of the metal cations, the particular trapping ability of the crown ether to metal cations could effectively reduce the electrostatic interaction between the metal cations and iodide anions to release more iodide anions. Electrochemical impedance analysis reveals that ∼35 fold of ionic conductivity enhancement for the multi-iodine doped ionic liquids can be obviously observed at room temperature. For applications, these multi-iodine doped crown ether functionalized ionic liquids can be used as gel electrolytes for dye-sensitized solar cells, displaying a power conversion efficiency of 3.86% at a simulated AM1.5 solar spectrum illumination at 100 mW cm−1. These preliminary results provide us with a feasible strategy to enhance the ionic conductivity and explore new ionic liquid electrolytes for energy storage and conversion devices.

A novel crown ether lithium salt complex [Li∈12-C-4][I] has been designed, synthesized and characterized. The thermal properties of the [Li∈12-C-4][I] based solid-state electrolytes were also investigated in detail. The particular trapping ability of 12-crown-4 to Li+ can obviously reduce the cation–anion (Li+–I−) interaction and hence facilitate favorable electrical properties of the solid-state electrolytes. Therefore, [Li∈12-C-4][I] represents ionic conductivity of 3.93 × 10−5 and 1.53 × 10−4 S cm−1 at 25 and 80 °C, respectively. Further addition of the ionic liquid 1-propyl-3-methylimidazolium iodine as a crystal growth inhibitor can effectively suppress the crystallization of the complex for more amorphous and smoother regions, which are much more conducive towards higher ion conductivity by the segmental motion of molecule chains. For application, the resulting device showed a power conversion efficiency of 5% and displayed excellent long-term stability. These results offer us more opportunities to explore simple and novel solid-state electrolytes for energy storage and conversion.