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Flexible heterojunction solar cells were fabricated from carbon nanotubes (CNTs) and mono-crystalline Si thin films at room temperature. The Si thin films with thickness less than 50 μm are prepared by chemically etching Si wafer in a KOH solution. The initial efficiency of the thin-film solar cell varies from approximately 3% to 5%. After doping with a few drops of 1 M HNO, the efficiency increases to 6% with a short-circuit current density of 16.8 mA/cm and a fill factor of 71.5%. The performance of the solar cells depends on the surface state and thickness of Si thin films, as well as the interface of CNT/Si. The flexible CNT/Si thin-film solar cells exhibit good stability in bending-recovery cycles. [ABSTRACT FROM AUTHOR]

A hybrid heterojunction and solid-state photoelectrochemical solar cell based on graphene woven fabrics (GWFs) and silicon is designed and fabricated. The GWFs are transferred onto n-Si to form a Schottky junction with an embedded polyvinyl alcohol based solid electrolyte. In the hybrid solar cell, solid electrolyte serves three purposes simutaneously; it is an anti-reflection layer, a chemical modification carrier, and a photoelectrochemical channel. The open-circuit voltage, short-circuit current density, and fill factor are all significantly improved, achieving an impressive power conversion efficiency of 11%. Solar cell models are constructed to confirm the hybrid working mechanism, with the heterojunction junction and photoelectrochemical effect functioning synergistically. [ABSTRACT FROM AUTHOR]

An unexpected behavior of graphene in graphene–silicon heterojunction junction solar cells when it is used as the window electrode is reported. Although the synthesized mono layer graphene exhibits better transparency and conductivity, the multilayer graphene enables much higher solar conversion ability of the solar cell. This surprising observation may be because the multilayer graphene can more effectively suppress charge recombination at the heterojunction interface, which increases the fill factor and enhances the cell performance. [ABSTRACT FROM AUTHOR]

High-efficiency micro core-shell solar cell (μ-CSSC) arrays are fabricated from Si wafer by using traditional lithography and phosphorus diffusion. The p-n junction depth is around 450 nm, indicating that it forms core-shell structure in micropillars by using phosphorus diffusion. The μ-CSSC arrays have high minority carrier lifetime of 23 μs and long diffusion length of ∼150 μm. The best power efficiency of the μ-CSSC reaches to 9.2%. It is a convenient method for fabricating Si μ-CSSC arrays in wafer scale for future applications. [ABSTRACT FROM AUTHOR]

A thin layer of ultraviolet-ozone (UVO) treated gold (Au) is introduced on multi-layer graphene (MLG) to enable the MLG as an effective anode for polymer solar cells (PSCs). By optimizing the Au thickness and the durations of the UVO treatments at different stages, MLG PSCs with enhanced fill factor and power conversion efficiency are obtained, exhibiting better performance compared with MLG devices directly modified with UVO and poly(3,4-ethylenedioythiophene):poly(styrenesulfonate). Further analysis shows that UVO treated Au provides favorable band alignment at the MLG/polymer interface. Moreover, the improved interfacial contact and shortened UVO durations reduce the series resistance of PSCs significantly. [ABSTRACT FROM AUTHOR]

Hybrid photoelectrochemistry and heterojunction solar cells made from carbon nanotubes and silicon nanowires show high energy conversion efficiencies of up to 6%. [ABSTRACT FROM AUTHOR]

Abstract: Carbon-based photovoltaic cells (PVCs) have attracted a great deal of interest for both scientific fundamentals and potential applications. In this paper, applications of various carbon materials in PVCs, especially in silicon-based solar cells, organic solar cells and dye-sensitized solar cells, are reviewed. The roles carbon materials played in the PVCs are discussed. Further research on solar cells comprised solely of carbon is prospected. [Copyright &y& Elsevier]

Abstract: N-doped carbon thin films (N-CFMs) on copper foils are synthesized by using acetonitrile (CH3CN) as liquid carbon and nitrogen precursors in a chemical vapor deposition system. Effect of acetonitrile feeding amount on the optical transmittance and electrical conductivity of N-CFMs are investigated. It is found that both the transmittance (from ∼41% to ∼75%) and sheet resistance (from ∼700Ω/sq to ∼2000Ω/sq) increases with the decrease of acetonitrile feeding amount (from 200μL to 10μL). Schottky junction solar cells based on n-type silicon and as-synthesized N-CFMs demonstrate power conversion efficiencies of up to ∼1.55%, showing their potential applications in photovoltaic areas. [Copyright &y& Elsevier]

Abstract: Carbon nanotube films with high nanotube loading were prepared using a vacuum filtration method and their photovoltaic properties as semi-transparent conducting electrodes in nanotube-silicon heterojunction solar cells were investigated. The correlation between the power conversion efficiency of the solar cells and the figure of merit (FM) of the films were obtained. The maximum efficiencies (up to 1.5%) were found for those cells using the films with highest FMs and transmittances. For comparison, the photovoltaic performance of a self-assembled nanotube thin film of high transmittance (91%) was tested and the corresponding solar cell showed a conversion efficiency of ∼4%. This work provides guidance for future improvement on the photovoltaic properties of nanotube films as window electrode materials. [ABSTRACT FROM AUTHOR]

Abstract: Copper iodide (CuI) has good electrical conductivity and is usually used as hole-injector, collector and transporter in solar cells. CuI particles are prepared on silicon wafer by metal-assisted etching method in Cu(NO3)2/HF solution and then iodizing in I2/ethanol solution. The size and density of the CuI particles are well controlled by tuning the etching time in Cu(NO3)2/HF solution. It forms a CNT–CuI–Si solar cell when a carbon nanotube (CNT) film covers on the Si substrate modified by CuI particles. The efficiency of the CNT–Si heterojunction cell modified by CuI particles reaches 6% in the initial test. The quantum efficiency of the CNT–Si cell with CuI modification is higher than that without CuI modification, which shows that CuI particles can enhance hole-collecting and transporting ability in the CNT-Si heterojunction solar cell. [Copyright &y& Elsevier]