The operation characteristics of nominal bilayer (BL) organic solar cells (OSCs), the active layers (ALs) of which consisted of sequentially casted bottom P3HT donor and top ICBA acceptor layers, resembled those of OSCs with bulk heterojunction (BHJ) ALs. Optical analysis and device simulations showed that such resemblance can be attributed to a similarity in the micromorphology of ALs; as‐deposited BL‐type ALs transformed spontaneously into BHJ‐type ALs. The inclusion of P3HT nanowires (NWs) in the donor layers resulted in different AL micromorphology and consequently a larger power conversion efficiency. Separate assessment of the exciton generation and charge–carrier transport and/or extraction showed that the contribution of P3HT NWs was more prominent in optical effects.
A significant conduction band offset appearing in n‐ZnO/p‐Si heterojunction solar cells is recognized as a serious roadblock to obtain high efficiency solar cells. By alloying with Mg, the conduction band in Zn1–xMgxO can be raised above that of Si, so that the influence of recombination centers at the interface between the two materials is strongly reduced, enabling high efficiency despite recombination velocities as high as 106 cm s−1. By simulating these phenomena we predict an optimal design of a n‐Zn0.8Mg0.2O/p‐Si solar cell resulting in high conversion efficiencies. 相似文献
Radial n–i–p structure silicon nanowires‐(SiNWs) based solar cells on flexible stainless steel substrates have been fabricated by plasma‐enhanced chemical vapor deposition (PECVD). The highest open‐circuit voltage (Voc) and short‐circuit current density (Jsc) for AM 1.5 illumination were 0.62 V and 13.36 mA cm−2, respectively, at a maximum power conversion efficiency of 3.56%. The optical reflectance of the SiNWs solar cells over a broad rang of wavelengths (300–1000 nm) is reduced by ∼80% in average compared to planar silicon thin film cells. The external quantum efficiency (EQE) measurements show that the EQE response of SiNWs solar cells is improved greatly in the wavelength range of 550–750 nm compared to corresponding planar silicon thin film solar cells. 相似文献
In this study, structural and optoelectronic properties and photodedection characteristics of diodes constructed from p-zinc telluride (ZnTe) thin film/n-silicon (Si) nanowire heterojunctions are reported. Dense arrays of vertically aligned Si nanowires were successfully synthesized on (1 1 0)-oriented n-type single crystalline Si wafer using simple and inexpensive metal-assisted etching (MAE) process. Following the nanowire synthesis, p-type ZnTe thin films were deposited onto vertically oriented Si nanowires via radio frequency magnetron sputtering to form three-dimensional heterojunctions. A comparative study of the structural results obtained from X-ray diffraction and Raman spectroscopy measurements showed the improved crystallinity of the ZnTe thin films deposited onto the Si nanowire arrays. The fabricated nanowire-based heterojunction devices exhibited remarkable diode characteristics and enhanced optoelectronic properties and photosensitivity in comparison to the planar reference. The electrical measurements revealed that the diodes with nanowires had a well-defined rectifying behaviour with a rectification ratio of 104 at ±2 V and a relatively small ideality factor of n = 1.8 with lower reverse leakage current and series resistance at room temperature in dark condition. Moreover, an open-circuit voltage of 100 mV was also observed under illumination. Based on spectral photoresponsivity measurements, the nanowire-based device exhibited a distinct responsivity and high detectivity in visible and near-infrared (NIR) wavelength regions. The device characteristics observed here offer that the fabricated ZnTe thin film/Si nanowire-based p–n heterojunction structures will find important applications in future and will be a promising candidate for high-performance and low-cost optoelectronic device applications, NIR photodedectors in particular. 相似文献
Theoretical investigations of InGaN tandem solar cells with intermediate bands (IBs) have been conducted through calculating the diode equation taking into account the radiative and nonradiative recombination currents. The calculated maximum ef?ciencies of the double‐junction cell with one IB in each subcell are 57.85% and 68.37% under AM1.5G one‐sun and 46000‐sun illuminations, respectively. It has also been observed that the combined device with the top‐cell bandgaps of 2.9–3.4 eV (2.6–3.4 eV for full concentration) may have an opportunity to realize the application of over 50% efficiency. We suggest that the optimized width of the IB layer be designed in the range of 1–6 μm if its absorption coefficient is 104–105 cm–1 in the IB region. 相似文献
The effects of interface polarization charge on the photovoltaic characteristics of GaN/InGaN solar cells have been analyzed in detail using 2D drift‐diffusion simulations. The polarization charge at the GaN/InGaN interface creates an electric field that forces carriers generated by light to drift in opposite direction needed for efficient collection and substantially reduces the short circuit current (Isc) and open circuit voltage (Voc). The polarization charge plays an important role in the photovoltaic properties of InGaN solar cells comparable to that of defects. For small interface charge, the potential barrier could increase the Voc. 相似文献
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