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Hybrid solar cells have been fabricated from solution processing of poly‐(3‐hexylthiophen‐2,5‐diyl) onto planar poly‐crystalline thin film silicon (poly‐Si) absorbers on glass. The poly‐Si layers were prepared by laser crystallization. Methyl passivation of the poly‐Si surface by a one‐step grafting process via methyl‐Grignard enabled open circuit voltages of up to 552 mV and an overall power conversion efficiency of 6.6% for this device type. The solar cell exhibited significant advantages compared to the wafer‐based counterparts. The inverted device structure of the thin film cell lead to an enhancement of the quantum efficiency since the back side contacted cell had less light absorption and reflection losses due to the gold layer which was used as front contact for the c‐Si‐based hybrid solar cell. As a result, a photo current of 24.3 mA cm−2was obtained for a 10 μm thin poly‐Si layer on glass. Furthermore, the inverted device structure showed a pronounced increase in stability due to the much thicker gold back contact that reduces the diffusion of water and oxygen toward the polymer layer. After 3 months in ambient air, this type of solar cell operated with 86% of its initial efficiency.

The loss of a functional microvascular bed in rejecting solid organ transplants is correlated with fibrotic remodeling and chronic rejection; in lung allografts, this pathology is predicted by bronchoalveolar fluid neutrophilia which suggests a role for polymorphonuclear cells in microcirculatory injury. In a mouse orthotopic tracheal transplant model, cyclosporine, which primarily inhibits T cells, failed as a monotherapy for preventing microvessel rejection and graft ischemia. To target neutrophil action that may be contributing to vascular injury, we examined the effect of a neutrophil elastase inhibitor, elafin, on the microvascular health of transplant tissue. We showed that elafin monotherapy prolonged microvascular perfusion and enhanced tissue oxygenation while diminishing the infiltration of neutrophils and macrophages and decreasing tissue deposition of complement C3 and the membrane attack complex, C5b‐9. Elafin was also found to promote angiogenesis through activation of the extracellular signal‐regulated kinase (ERK) signaling pathway but was insufficient as a single agent to completely prevent tissue ischemia during acute rejection episodes. However, when combined with cyclosporine, elafin effectively preserved airway microvascular perfusion and oxygenation. The therapeutic strategy of targeting neutrophil elastase activity alongside standard immunosuppression during acute rejection episodes may be an effective approach for preventing the development of irreversible fibrotic remodeling. Using a mouse orthotopic tracheal transplantation model, the authors show that cyclosporine fails to protect the microvasculature of airway transplants undergoing acute rejection, but combined therapy with cyclosporine and a neutrophil elastase inhibitor, elafin, synergistically promotes the microvascular perfusion and improves the transplant structural integrity.

The defect properties of lasercrystallized polycrystalline silicon–germanium Si–Ge thin films on glass substrates were investigated with electron spin resonance ESR and conductivity measurements. The ESR measurements reveal that lasercrystallized poly Si1−xGexthin films with 0 < x < 0.84 contain a danglingbond concentration of about Ns  4 × 1018 cm−3, roughly independent of the Ge content in this range. Surprisingly, the ESR signal vanishes completely for the Gerich alloys x > 0.84 and instead a broad atypical signal appears that we attribute to electric dipole induced spin resonance EDSR. Samples that showed this behavior exhibited a nearly temperatureindependent electrical conductivity for temperatures between 20 and 100 K. The data are discussed in terms of a model that is based on the formation of a defect band along the grain boundaries in the vicinity of the Fermi level.

Raman measurements of heavily doped laser crystallized poly-Si and as-deposited μc-SH show significant differences between the two materials. Poly-Si samples exhibit the Fano effect just like heavily doped c-Si samples. This is not true for the heavily doped μc-SH samples.

Raman measurements of heavily doped laser crystallized poly-Si and as-deposited μc-SH show significant differences between the two materials. Poly-Si samples exhibit the Fano effect just like heavily doped c-Si samples. This is not true for the heavily doped μc-SH samples.

The influence of the solvent on the halide exchange reaction of methylammonium lead tri-iodide (MAPbI3) by bromide ions in solution by forming bromide related plumbates like PBr3–or PbBr42–was investigated by photoluminescence (PL) spectroscopy. Dimethyl sulfoxide (DMSO), γ-butyrolactone (GBL) and N,N-dimethylformamide (DMF) were used as coordinating solvents. It was found that iodide is slowly replaced by bromide ions using DMSO and DMF. In the case of DMSO, we calculated an exchange of about 15 mol % of the initial MAPbI3concentration within 100 h using equimolar amounts of KBr. Surprisingly, using GBL as solvent leads to very small exchange of PbI3–ions to PbBr3–/PbBr42–ions even after 7 days. Furthermore, the PL investigation reveals that if PbI42–is formed iodide is no longer replaced by bromide ions. Both effects are sustained by DFT calculations that support electronic shielding of the formed complexes against exchange with bromide anions.

The optical spectra (1–10 eV) of plasma deposited films of a-Si1−xNx:H have been studied in the range 0≤x≤0.57 (stoichiometric a-Si3N4:H). It is found that up to x=0.3 the dielectric function ∈2(ω) is mainly determined by the concentration of SiSi bonds. For x>0.3 the number of SiSi bonds becomes too small to allow the existence of a connected Si-network and the spectra reveal the contribution of Si-N bonds at higher energy. This change from Si-like to SiNi-like behavior occurs when about 60 % of the SiSi bonds have been substituted which is close to the threshold for bond percolation in a tetrahedral network.

Metastable changes in a-Si: H/a-SiNx: H TFTs caused by prolonged application of high gate voltages and by light exposure are studied by measurements of the transfer characteristics and by a transient current spectroscopy (TCS). Voltage stress leads to a strong shift of the threshold voltage due to charge trapping in the nitride and also to the creation of metastable defects in the accumulation layer. This voltage-induced defect generation is thermally activated with an energy near 0·7 eV and therefore, at room temperature, is less effective than defect creation by light soaking.

Graphene has become an extremely prospective material for numerous applications because of its excellent electrical and optical properties. The combination of conductivity and high transparency and the ability of large‐area production render graphene suitable as a contact layer and transparent electrode in solar cells. Graphene brought into direct contact with n‐type silicon introduces a built‐in electric field at the heterojunction interface and forms a Schottky contact. Solar cells utilizing this effect show a conversion efficiency of 4.2%. However, the graphene‐Si Schottky diodes are not stable and degrade strongly during the first days. In the study by Brus et al. (pp. 843–847) the influence of the graphene‐silicon interface on the solar cell properties is investigated. The quality of this interface is crucial since the concentration of localized states and its ability to block minority carriers influence the device performance significantly. Passivation of the silicon surface with methyl groups prior to graphene deposition reduces recombination loss at the graphene/Si heterojunction. In addition, it enhances and stabilizes the photoelectric performance of undoped graphene/n‐type c‐Si(111) solar cells.