Poly(amidoamine) Dendrimer as an Interfacial Dipole Modification in Crystalline Silicon Solar Cells

Poly(amidoamine) (PAMAM) dendrimers are used to modify the interface of metal-semiconductor junctions. The large number of protonated amines contributes to the formation of a dipole layer, which finally serves to form electron selective contacts in silicon heterojunction solar cells. By modifying the work function of the contacts, the addition of the PAMAM dendrimer interlayer quenches Fermi level pinning, thus creating an ohmic contact between the metal and the semiconductor. This is supported by the observation of a low contact resistivity of 4.5 mΩ cm2, the shift in work function, and the n-type behavior of PAMAM dendrimer films on the surface of crystalline silicon. A silicon heterojunction solar cell containing the PAMAM dendrimer interlayer is presented, which achieved a power conversion efficiency of 14.5%, an increase of 8.3% over the reference device without the dipole interlayer

Inkjet‐Printed p‐NiO/n‐ZnO Heterojunction Diodes for Photodetection Applications

Transparent Conducting Oxides (TCOs) are an enticing family of optoelectronic materials which have been proven to increase efficiency when incorporated into perovskite light emitting diode (PE-LED) and organic OLED architectures as transport layers. Solution-processed metal oxide inks have already been demonstrated, although there is still a need for high-quality inkjet-printable metal oxide inks with a thermal post-process below 200 °C. The set of inks in this work are adapted from low-boiling point colloidal suspensions of metal oxide nanoparticles synthesized via flame spray pyrolysis. High quality, pinhole- and wrinkle-free inkjet-printed layers are obtained at low temperatures through vacuum oven post process, as proven by scanning electron microscopy. The crystallinity of the layers is confirmed by X-ray diffraction, showing the expected hexagonal and cubic structures respectively for ZnO and NiO. The thin film layers reach over 70% (ZnO) and 90% (NiO) transparency in the visible spectrum. Their implementation in the inkjet-printed p-n diode shows excellent I-V rectifying behavior with an ON/OFF ratio of two orders of magnitude at ±3 V and a forward threshold voltage of 2 V. Furthermore, the device exhibits an increase in photocurrent around four orders of magnitude when illuminated under a 1-sun solar simulator

Polymeric Interlayer in CdS-Free Electron-Selective Contact for Sb2Se3 Thin-Film Solar Cells

High open-circuit voltage in Sb2Se3 thin-film solar cells is a key challenge in the development of earth-abundant photovoltaic devices. CdS selective layers have been used as the standard electron contact in this technology. Long-term scalability issues due to cadmium toxicity and environmental impact are of great concern. In this study, we propose a ZnO-based buffer layer with a polymer-film-modified top interface to replace CdS in Sb2Se3 photovoltaic devices. The branched polyethylenimine layer at the ZnO and transparent electrode interface enhanced the performance of Sb2Se3 solar cells. An important increase in open-circuit voltage from 243 mV to 344 mV and a maximum efficiency of 2.4% was achieved. This study attempts to establish a relation between the use of conjugated polyelectrolyte thin films in chalcogenide photovoltaics and the resulting device improvements

Polymeric interlayer in CdS-free Electron-Selective Contact for Sb2Se3 thin-film solar cells

High open-circuit voltage in Sb2Se3 thin-film solar cells is a key challenge in the development of earth-abundant photovoltaic devices. CdS selective layers have been used as the standard electron contact in this technology. Long-term scalability issues due to cadmium toxicity and environmental impact are of great concern. In this study, we propose a ZnO-based buffer layer with a polymer-film-modified top interface to replace CdS in Sb2Se3 photovoltaic devices. The branched polyethylenimine layer at the ZnO and transparent electrode interface enhanced the performance of Sb2Se3 solar cells. An important increase in open-circuit voltage from 243 mV to 344 mV and a maximum efficiency of 2.4% was achieved. This study attempts to establish a relation between the use of conjugated polyelectrolyte thin films in chalcogenide photovoltaics and the resulting device improvements

Absence of free carriers in silicon nanocrystals grown from phosphorus- and boron-doped silicon-rich oxide and oxynitride

Phosphorus- and boron-doped silicon nanocrystals (Si NCs) embedded in silicon oxide matrix can be fabricated by plasma-enhanced chemical vapour deposition (PECVD). Conventionally, SiH4 and N2O are used as precursor gasses, which inevitably leads to the incorporation of ≈10 atom % nitrogen, rendering the matrix a silicon oxynitride. Alternatively, SiH4 and O2 can be used, which allows for completely N-free silicon oxide. In this work, we investigate the properties of B- and P-incorporating Si NCs embedded in pure silicon oxide compared to silicon oxynitride by atom probe tomography (APT), low-temperature photoluminescence (PL), transient transmission (TT), and current–voltage (I–V) measurements. The results clearly show that no free carriers, neither from P- nor from B-doping, exist in the Si NCs, although in some configurations charge carriers can be generated by electric field ionization. The absence of free carriers in Si NCs ≤5 nm in diameter despite the presence of P- or B-atoms has severe implications for future applications of conventional impurity doping of Si in sub-10 nm technology nodes

Resistive switching and charge transport mechanisms in ITO/ZnO/p-Si devices

The resistive switching properties of ITO/ZnO/p-Si devices have been studied, which present welldefined resistance states with more than five orders of magnitude difference in current. Both the high resistance state (HRS) and the low resistance state (LRS) were induced by either sweeping or pulsing the voltage, observing some differences in the HRS. Finally, the charge transport mechanisms dominating the pristine, HRS, and LRS states have been analyzed in depth, and the obtained structural parameters suggest a partial re-oxidation of the conductive nanofilaments and a reduction of the effective conductive area. Published by AIP Publishing. https://doi.org/10.1063/1.504691