Planar Hybrid Solar Cells Research Articles

Enhancement of Photoelectric Performance Based on Ultrathin Wide Spectrum Solar Absorption in Cruciform Microstructure Germanium Solar Cells

In this paper, the solar absorption level of PEDOT:PSS/Ge organic and inorganic hybrid solar cells (HSCs) with different parameters of cruciform microstructure (CM) is studied, using the finite-difference time domain (FDTD) method. The light absorption in HSCs with CM is above 90% in the range of 300 nm to 1300 nm. Under the AM1.5 solar spectrum, the average absorptivity of solar energy is also at a very high level. At the same time, we use DEVICE software to calculate the electrical properties, such as the open-circuit voltage (Voc), short-circuit current density (Jsc), and maximum power density (Pmax). The electrical simulation results show that the Pmax of HSCs with CM improves to 72.16% from the planar HSCs. Besides, in order to study the mechanism of solar energy absorption in HSCs containing CM, the logarithmic plots of electric field intensity of HSCs with CM and planar HSCs, are analyzed at different wavelengths. The work shows that the CM shows an excellent light-trapping effect, which reduces the surface reflectivity of HSCs, and greatly improves the photoelectric conversion efficiency of Ge solar cells.

Controlling of Conductivity and Morphological Properties of Hole-Transport Layer Using Ionic Liquid for Vacuum-Free Planar Hybrid Solar Cells

In this study, an acidic (A) and pH-neutral (pHN) solution using poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) as the hole-transport layer (HTL) was modified using a 1-butyl-3-methylimidazolium chloride (BMIM+Cl−) ionic liquid (IL). The effects of this ionic liquid on the conductivity and morphological properties of the PEDOT:PSS films were investigated. The conductivity and morphological properties of the PEDOT: PSS films before and after adding IL were measured using a UV–vis spectrophotometer and atomic force microscope (AFM), respectively. The conductivity of the A-PEDOT:PSS-film-based ionic liquid was decreased, while the conductivity of the pHN-PEDOT:PSS-film-based ionic liquid was increased. The surface morphology of the A-PEDOT:PSS-film-based ionic liquid was slightly decreased, while the conductivity of the pHN-PEDOT:PSS-film-based ionic liquid was slightly increased. The vacuum-free planar hybrid solar cells (VFPHSCs) using the pHN-PEDOT:PSS-film-based ionic liquid show a higher power conversion efficiency (PCE) than the VFPHSCs using the A-PEDOT:PSS-film-based ionic liquid. We also report that a solar cell with a structure of ITO/pHN-PEDOT:PSS/PTB7:PCBM/PEO/EGaIn has a maximum PCE of about ~5%.

Numerical study of efficient ternary planar hybrid solar cells using simple boron molecules as organic compounds

Ternary solar cells have proven to be a solution to absorb more photons at different wavelengths and reduce the recombination of charge carriers. Here, we propose a new hybrid organic-inorganic ternary planar solar-cell structure using a novel boron compound. The role of this material on the performance of the device with a polymer/borinate/ZnO configuration is studied. As the donor polymer, we evaluate P3HT, PTB7, and PCPDTBT; and three boron compounds with different properties, especially concerning the bandgap and trap energy depth. To validate the experimental electrical characteristics of the borinates, first, we simulate a bilayer structure with C60, subsequently, we simulate and analyze the whole device architecture. The ternary solar cell with PTB7 and a borinate with a bandgap of 1.66 eV and a medium trap energy depth of 0.95 eV above the HOMO level exhibit the highest efficiency, i. e. 11.7%. Furthermore, we present a layer thickness optimization of the materials to reach even higher efficiencies, up to 15.15%. Finally, the effect of the magnitude of the density of trap states in the borinate on the device performance is analyzed.

Vacuum-Free Quantum Dots Planar Hybrid Solar Cells: Improving Charge Transport Using Reduced Graphene Oxide and PEO as the Buffer Layer

In this work, reduced graphene oxide (rGO) was synthesized using a modified Hummer method and its morphological and structural properties were investigated using transmission electron microscopy (TEM), high-resolution TEM (HR-TEM) and X-ray diffraction (XRD). The rGO was used as the hole transport buffer layer (HTBL) and poly(ethylene oxide) (PEO) was used as the electron transport buffer layer (ETBL) for the vacuum-free quantum dot planar hybrid (VFQPH) solar cells (SCs) fabrication. PbS quantum dots (Qdots) were prepared using a hot-injection method, which was used as the p-type material and PCBM ([6,6]-Phenyl-C61-butyric acid methyl ester) was used as the n-type material. The effects of the hole transport buffer layer and electron transport buffer layer on the morphological and electrical properties of the device were investigated. A device with a structure of glass/indium tin oxide (ITO)/HTBL/PbS: PCBM/ETBL/E-GaIn was fabricated and the maximum power conversion efficiency of about 4.34% was obtained.

Hybrid solar cells from Sb2S3 nanoparticle ink

Sb2S3 is a promising candidate for solar cell absorbers due to its high absorption coefficient, suitable band gap and earth-abundant constituents. Here we present the preparation of hybrid solar cells from an ink of colloidal Sb2S3 nanoparticles and P3HT. Colloidal Sb2S3 nanoparticles were prepared via hot injection method. Solar cells based on these nanoparticles achieves a power conversion efficiency of 1.5%, which is efficiency record for planar hybrid solar cells based on Sb2S3 nanoparticles. We investigated in detail the role of the capping agents on the performance of solar cells.

Limiting factors of photon-to-current conversion in polymer/nanocrystal bilayer hybrid solar cells: An analytical quantum efficiency model study

This paper introduces an analytical external quantum efficiency (EQE) model of planar hybrid solar cells (HSCs) based on photon-to-current conversion processes and uses this to investigate the factors that limit the maximum EQE (EQEm) of devices; i.e., the photon absorption coefficient α, exciton diffusion coefficient Dz, exciton lifetime τz, exciton dissociation rate kdis, electron diffusion coefficient De, electron lifetime τe, nanocrystals thickness d, and thickness of the polymer l. Our simulations indicate that relying solely on modifying kdis, De, or τe cannot achieve a breakthrough increase in the EQEm of planar HSCs. However, increasing α, Dz, or τz could potentially lead to a large EQEm (30–100%), especially in the context of high kdis values. Moreover, the calculation results indicate that although both Dz and τz contribute to the exciton diffusion length (Lz) via the equation Lz2 = Dzτz, the EQEm has an asymmetric dependence on these variables. With a small kdis (i.e., <104 cm/s), an increase in Dz results in an initial increase and then decrease in EQEm, resulting in a peak value that increases with increasing kdis. When kdis is sufficiently large (∼105 cm/s), the EQEm becomes saturated after the initial increase. Thus, although an increase in Dz can adversely affect device performance when the kdis is lower than 104 cm/s, increasing τz always improves device performance, regardless of large kdis becomes. This behavior can be attributed to the detrimental effect of excitons accumulating at the D/A interface, and can be used to optimize the material design and device engineering of planar HSCs and related solar cells for maximum photon-to-current conversion performance. In addition, we also demonstrate that the model can fit to the experimental data.

Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)/GaAs hybrid solar cells with 13% power conversion efficiency using front- and back-surface field.

PSS) demonstrated an excellent power conversion efficiency of 8.99%. The efficiency of the cell was enhanced to 9.87% with a back-surface field feature using a molecular beam epitaxially grown n-type GaAs epi-layer. The efficiency and fill factor reach 11.86% and 0.8 when an additional p + GaAs epi-layer is deposited on the surface of the solar cells, which provides a front-surface field. The interface between the high- and low-doped regions in the polymer/GaAs and GaAs formed an electric field that introduced a barrier to minority carriers flow to the substrate and effectively reduced front surface carrier recombination, thereby enhancing light-generated free carrier collection efficiency and open-circuit voltage. Compared with the device without the front- and back-surface field, the fill factor and open-circuit voltage of the hybrid solar cell were improved from 0.76 to 0.8 and from 0.68 V to 0.77V, respectively. The highest efficiency reaches a record 13% when the Zonyl fluorosurfactant-treated PSS is used as a hole-transporting conducting layer for hybrid cells.

Hysteresis-less inverted CH3NH3PbI3 planar perovskite hybrid solar cells with 18.1% power conversion efficiency

The inverted CH3NH3PbI3 planar hybrid solar cells exhibited better device efficiency and stability and lower hysteresis than the normal cells.