We present a detailed analysis of the photo-current potentials and losses in thin film crystalline silicon solar cells on glass. The effects of texturing the silicon backside, applying a diffuse back ...reflector and a textured anti-reflection foil were analysed. Light beam induced current measurements were used to determine the losses due to local effects like the absorber contact, cracks in the absorber and grain boundaries. Detailed loss analysis in combination with ray-tracing simulations showed that the maximum light trapping potential imposed by geometrical optics has nearly been achieved. The photocurrent losses due to incomplete carrier collection and parasitic absorption were accounted for using a theoretical model. For the investigated, textured, n-doped cell with reflector and anti-reflection foil, the short circuit current density (JSC) was 28.9mA/cm2 and the main loss factors were direct reflection (3.4mA/cm2), electrical shading effects due to the absorber contact (3.1mA/cm2) and incomplete carrier collection due to surface/bulk recombination (1.6mA/cm2). Using the presented light trapping scheme we obtained the following efficiencies: 11.8% for a p-doped and 12.1% for an n-doped crystalline silicon absorber. Finally, the potentials for efficiencies beyond 14% are discussed.
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•12 % efficiency was obtained for 11 µm thick, liquid-phase crystalized Si on glass.•Using KOH texturing and anti-reflection foil, a JSC of 28.9 mA/cm2 was achieved.•Current density losses were characterized using LBIC, optics, EQE and simulations.•Main loss factors were direct reflection, the absorber contact and recombination.•Max. light trapping potential was almost reached, using a backside pyramid texture.
The TCO/a-Si:H(p) contact is a critical part of the silicon heterojunction solar cell. At this point, holes from the emitter have to recombine loss free with electrons from the TCO. Since tunneling ...is believed to be the dominant transport mechanism, a high dopant density in both adjacent layers is critical. In contrast to this, it has been reported that high TCO dopant density can reduce field effect passivation induced by the a-Si:H(p) layer. Thus, in this publication, we systematically investigate the influence of a thin (∼10 nm) ITO contact layer with dopant densities ranging from Nd = 1019 - 1021 cm-3 placed between an ITO bulk layer of 70 nm with Nd= 2·1020 cm-3 and the a-Si:H(p) emitter on the J-V characteristics, with the aim to find an optimum Nd. We accompanied our experiments by AFORS-HET simulations, considering trap-assisted tunneling and field dependent mobilities in the a-Si:H(p) layer. As expected, two regimes are visible: For low Nd the devices are limited by inefficient tunneling, resulting in S-shaped J-V characteristics. For high Nd a reduction of the field effect passivation becomes visible in the low injection range. We can qualitatively reproduce these findings using device simulations.
In this study, various silicon dielectric films, namely, a-SiO x :H, a-SiN x :H, and a-SiO x N y :H, grown by plasma enhanced chemical vapor deposition (PECVD) were evaluated for use as interlayers ...(ILs) between crystalline silicon and glass. Chemical bonding analysis using Fourier transform infrared spectroscopy showed that high values of oxidant gases (CO2 and/or N2), added to SiH4 during PECVD, reduced the Si–H and N–H bond density in the silicon dielectrics. Various three layer stacks combining the silicon dielectric materials were designed to minimize optical losses between silicon and glass in rear side contacted heterojunction pn test cells. The PECVD grown silicon dielectrics retained their functionality despite being subjected to harsh subsequent processing such as crystallization of the silicon at 1414 °C or above. High values of short circuit current density (J sc; without additional hydrogen passivation) required a high density of Si–H bonds and for the nitrogen containing films, additionally, a high N–H bond density. Concurrently high values of both J sc and open circuit voltage V oc were only observed when Si–H was equal to or exceeded N–H. Generally, V oc correlated with a high density of Si–H bonds in the silicon dielectric; otherwise, additional hydrogen passivation using an active plasma process was required. The highest V oc ∼ 560 mV, for a silicon acceptor concentration of about 1016 cm–3, was observed for stacks where an a-SiO x N y :H film was adjacent to the silicon. Regardless of the cell absorber thickness, field effect passivation of the buried silicon surface by the silicon dielectric was mandatory for efficient collection of carriers generated from short wavelength light (in the vicinity of the glass–Si interface). However, additional hydrogen passivation was obligatory for an increased diffusion length of the photogenerated carriers and thus J sc in solar cells with thicker absorbers.
Liquid-phase crystallized silicon absorber layers have been applied in heterojunction solar cells on glass substrates with 10.8% conversion efficiency and an open-circuit voltage of 600 mV. ...Intermediate layers of SiO x , SiN x , and SiO x N y , as well as the a-Si:H precursor layer, were deposited on 30 cm × 30 cm glass substrates using industrial-type plasma-enhanced chemical vapor deposition equipment. After crystallization on 3cm × 5cm area using a continuous-wave infrared laser line, the resulting polysilicon material showed high material quality with large grain sizes.
Microcrystalline silicon (μc-Si:H) thin-film solar cells are processed on glass superstrates having both micro- and nanoscale surface textures. The microscale texture is realised at the glass ...surface, using the aluminium-induced texturing (AIT) method, which is an industrially feasible process enabling a wide range of surface feature sizes (i.e., 700 nm–3 μm) of the textured glass. The nanoscale texture is made by conventional acid etching of the sputter-deposited transparent conductive oxide (TCO). The influence of the resulting “double texture” on the optical scattering is investigated by means of atomic force microscopy (AFM) (studying the surface topology), haze measurements (studying scattering into air), and short-circuit current enhancement measurements (studying scattering into silicon). A predicted enhanced optical scattering efficiency is experimentally proven by a short-circuit current enhancement Δ I sc of up to 1.6 mA/cm2 (7.7% relative increase) compared to solar cells fabricated on a standard superstrate, that is, planar glass covered with nanotextured TCO. Enhancing the autocorrelation length (or feature size) of the AIT superstrates might have the large potential to improve the μc-Si:H thin-film solar cell efficiency, by reducing the shunting probability of the device while maintaining a high optical scattering performance.
Interleukin-1 receptor-associated kinase 4 (IRAK4) plays a critical role in innate inflammatory processes. Here, we describe the discovery of two clinical candidate IRAK4 inhibitors, BAY1834845 ...(zabedosertib) and BAY1830839, starting from a high-throughput screening hit derived from Bayer’s compound library. By exploiting binding site features distinct to IRAK4 using an in-house docking model, liabilities of the original hit could surprisingly be overcome to confer both candidates with a unique combination of good potency and selectivity. Favorable DMPK profiles and activity in animal inflammation models led to the selection of these two compounds for clinical development in patients.
The growth of uterine fibroids is sex hormone-dependent and commonly associated with highly incapacitating symptoms. Most treatment options consist of the control of these hormonal effects, ...ultimately blocking proliferative estrogen signaling (i.e., oral contraceptives/antagonization of human gonadotropin-releasing hormone receptor hGnRH-R activity). Full hGnRH-R blockade, however, results in menopausal symptoms and affects bone mineralization, thus limiting treatment duration or demanding estrogen add-back approaches. To overcome such issues, we aimed to identify novel, small-molecule hGnRH-R antagonists. This led to the discovery of compound BAY 1214784, an orally available, potent, and selective hGnRH-R antagonist. Altering the geminal dimethylindoline core of the initial hit compound to a spiroindoline system significantly improved GnRH-R antagonist potencies across several species, mandatory for a successful compound optimization in vivo. In a first-in-human study in postmenopausal women, once daily treatment with BAY 1214784 effectively lowered plasma luteinizing hormone levels by up to 49%, at the same time being associated with low pharmacokinetic variability and good tolerability.
A novel emitter patterning method for back-contacted Si heterojunction solar cells is presented, which combines laser processing and wet etching of a mask layer stack with self-aligned repassivation, ...thus reducing the process complexity, as compared with the commonly used emitter patterning methods. Lifetime samples demonstrate that with a suitable mask stack, laser scribing can be performed without inducing laser damage to the passivation. Despite nonoptimal wet etch and repassivation processes which currently limit the obtained lifetime, proof-of-concept cells on p-type wafers fabricated using this novel emitter patterning process and lithographically patterned metallization exhibit an open-circuit voltage of 694 mV and pseudo-fill-factors of 83%. With the laser written mask layers for etching and self-aligned passivation process, we have thus developed the proof-of-concept for a simple, lithography free, and contactless emitter patterning method for industrial applications.
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