Amorphous silicon-based absorbers have re-emerged in recent years as a good choice for implementing highly reliable transparent photovoltaic devices. While this technology ensures long-term stability and scalability, amorphous silicon exhibits relatively high absorption in the ultraviolet and visible part of the spectrum. This work reports on the use of hydrogenated amorphous silicon-carbon (a-Si1-xCx:H) films as a transparent absorber. By varying the carbon content, the properties of the absorber can be tuned, resulting in transparent devices with average photopic transmittance greater than 60 % and a light utilization efficiency of approximately 1.3 %. Additionally, the introduction of carbon enhances solar cell performance under low light irradiance, which is a typical condition in indoor photovoltaic applications.

This study investigates selective femtosecond infrared laser ablation of ultrathin VOx, MoOx, and WOx films deposited on crystalline silicon, targeting residue-free patterning without modifying the substrate. A 1030 nm, 320 fs laser was used to quantify the fluence thresholds for complete film removal and substrate damage, thereby defining a selective processing window for each oxide. Thresholds and beam radius were extracted from single-pulse crater diameters using the established Gaussian-beam crater-diameter method. Confocal 3D microscopy was employed to characterize crater morphology and groove continuity, and to relate process outcomes to fluence and pulse overlap constraints during high-speed scribing. Finally, diode isolation experiments show a reduction of reverse leakage current after laser scribing, supporting the suitability of femtosecond laser patterning for defining active areas in TMO/Si device stacks.

Selective charge extraction is a central limitation in heterogeneous photocatalysis, where short carrier diffusion lengths and interfacial recombination strongly restrict efficiency. Here we translate the photovoltaic concept of selective contacts to photocatalytic systems by designing interdigitated front architectures on a planar TiO2 absorber. Magnesium-magnesium oxide (Mg-MgOx) is used as an electron-selective layer, while gold nanoparticles act simultaneously as hole-selective contacts, plasmonic enhancers, and charge-transfer mediators toward gas-phase reactants. Interdigitated Mg-MgOx/Au patterns with controlled coverage and perimeter were fabricated on sol-gel anatase TiO2 films and tested for hydrogen production from ethanol-water vapor mixtures under UV illumination. While Au nanoparticles alone strongly enhance activity through efficient hole extraction and plasmonic effects, the addition of Mg-MgOx enables selective electron collection. However, performance is not governed by Mg-MgOx coverage alone. Samples with similar Mg-MgOx area fractions but different geometries show markedly different hydrogen production rates. To rationalize this behavior, we introduce a dimensionless geometric parameter eta, defined as the normalized ratio between selective-contact perimeter and coverage. Hydrogen production follows a Langmuir-Hinshelwood-type kinetic model when expressed as a function of eta, demonstrating that interfacial length, rather than area alone, controls the number of photogenerated carriers that reach adsorbed reactants before recombining. Highly interdigitated samples show up to a twofold increase in hydrogen production compared to non-patterned TiO2/Au references, despite having comparable material composition.

Transparent photovoltaic (TPV) devices represent a promising advance in photovoltaic technologies, particularly in building‐integrated photovoltaics (BIPV). Unlike conventional photovoltaics, which primarily prioritize efficiency, TPV must balance between efficiency, transparency, and aesthetics. These additional dimensions introduce unique challenges on device architecture. This article reports the development of wide‐bandgap, inorganic‐based TPV devices integrating ultrathin hydrogenated amorphous silicon (a‐Si:H) as a transparent absorber, with carrier selective contacts and transparent electrodes. The article analyzes how absorber thickness influences the electrical, optical, and aesthetic performance of devices, evaluating key parameters in TPV such as light utilization efficiency (LUE), average photopic transmittance (APT), color rendering index (CRI), and electrical properties such as power conversion efficiency (PCE). The device structure is SLG/FTO/AZO/a‐SiCx(n)/a‐Si:H/V2Ox/AZO. This approach results in PCE ranging from 1.7% with an APT of 60% to a PCE of 4.1% with an APT of 28%, yielding LUE values between 0.9% and 1.3%. Device characterization encompasses optical spectrophotometry, J–V measurements under standard test conditions, spectral response analysis, and variable illumination measurements (VIM). Additionally, color characterization is conducted using CIE 1931 color space maps to determine the chromaticity coordinates, CRI, and the variation of color as a function of absorber thickness.

This work reports a new thermal treatment approach to obtain [001]‐oriented Sb 2 Se 3 film, which consists of preliminary annealing of the Sb layer before its selenization. Among the different Sb annealing temperatures assessed, the one at 200 °C followed by selenization (Sb 2 Se 3 (Sb‐A200)) results in a considerably high texture coefficient at the [001] direction, whereas the Sb 2 Se 3 film obtained only by selenization of the non‐annealed Sb film (Sb 2 Se 3 (Sb‐NA)) features preferential orientation at the [ hk 0] direction. In terms of photoelectrochemical (PEC) performance for H 2 generation, the Sb 2 Se 3 (Sb‐A200)/CdS/TiO 2 /Pt film delivers a substantial photocurrent density of −5.65 mA cm −2 at 0 V RHE , which is 10 times higher compared to the Sb 2 Se 3 (Sb‐NA)/CdS/TiO 2 /Pt film. Additionally, the employment of the Sb annealing step results in stable PEC performance of the Sb 2 Se 3 film over 7000 s, meaning that the photocorrosion is minimized. The improved PEC performance of the Sb 2 Se 3 film is attributed to better crystallinity and composition closer to the stoichiometric condition, as well as the preferential orientation at the [001] direction that favors charger carriers' transportation. At last, the findings of this work feature an innovative thermal treatment approach to obtain [001]‐oriented Sb 2 Se 3 film to further improve H 2 generation from PEC water splitting.

Thin-film solar cells based on kesterite (Cu2ZnSnSe4) material are a promising alternative for photovoltaic devices due to their composition consisting of earth abundant elements, ease of production at a relatively low temperatures and excellent optical absorption properties. Additionally, this absorber compound allows a tuneable bandgap energy in the 1 to 1.5 eV window range, which makes it an attractive candidate either as a top or a bottom solar cell in tandem technologies combined with transparent carrier-selective contacts. However, conventional kesterite devices use a toxic CdS layer as an electron-selective contact, resulting in the difficult-to-dispose chemical waste. This work explores the use of a stack of ZnO and Al-doped ZnO (AZO) films deposited by ALD to replace the CdS-based contacts in kesterite devices. The inclusion of a polyethylenimine (PEI) interlayer as dipole to enhance the overall electrical contact performance is also discussed. The transparent back contact is formed by an ALD V2Ox thin layer over a FTO conductive electrode. Fabricated kesterite solar cells exhibit remarkable photocurrent density values of 35 mAcm(-2), open-circuit voltage around 260 mV and efficiencies up to 3.5% using front illumination. The aforementioned photovoltaic parameters yield to 5.3 mAcm(-2), 160 mV and 0.3% respectively under back illumination, demonstrating the bifaciality of the proposed structure.

Laser scribing is a promising technology for thin-film ablation in photovoltaic device manufacturing, particularly with non-conventional materials. This study explores copper oxides as alternative light absorbers due to their abundance and safe sourcing. Transition metal oxide (TMO) layers, like molybdenum oxide (MoO3), vanadium oxide (V2O5), and tungsten oxide (WO3), are investigated as selective contacts for advanced semiconductor devices. The research employs a high-powered fs laser (EKSPLA FemtoLux30, 30W, 1030 nm) with tunable pulse lengths (350 fs~1ps) and various wavelengths (1064, 532, and 355 nm) to determine the threshold ablation fluence and achieve optimal thin-film removal without substrate alteration. Diode isolation and electrical characteristics demonstrate the process's high quality.

At the junction between a metal and a semiconductor there are always charge transfer phenomena that can disrupt a selective or ohmic contact. This are result of workfunction mismatches either forming a Schottky junction or by Fermi Level Pinning. This effects unless they are used for a specific purpose within the device, can be detrimental to overall efficiency of a photovoltaic solar cell. Dipole thin films are known to modify surface energy being able to completely disrupt fermi level pinning and modify Schottky junction energy barrier. In this work a summary of several dipoles sharing some similarities between them such as PFN, PEI, DNA and PAMAM have been used to prove that upscaling the strength of dipole layers provide enhanced photovoltaic results when in combination with the metallic electrode.

Transparent photovoltaic (TPV) devices have the potential to revolutionize photovoltaic (PV) technology by enabling on‐site generation while minimizing visual impact. However, a major challenge in the development of TPV, as well as for many PV technologies, is the open‐circuit voltage ( V oc ) deficit, which limits their efficiency. In this work, the development of wide‐bandgap inorganic‐based TPV devices is reported with a focus on low‐cost, earth‐abundant, stable, and nontoxic materials. The device structure consists of an ultrathin hydrogenated amorphous silicon (a‐Si:H) absorber and metal‐oxide layers as selective contacts. Herein, novel approach is presented to significantly improve device performance, especially in V oc , by introducing molecular dipoles in the device electron‐transport layer. By incorporating polyethyleneimine or poly(amidoamine) G 1 and G 2 dipoles, V oc (from 410 mV up to 638 mV) is significantly increased without sacrificing the average photopic transmittance of the device, leading to a record efficiency for this particular approach in TPV. Measurements confirm excellent long‐term stability. This approach can potentially allow tuning the work function of the selective contacts enabling the use of low‐cost, earth‐abundant materials that are not optimized for a particular absorber. Furthermore, this solution circumvents the issue of low V oc by a simple interface treatment.

Synergistic interaction between 2D materials and organic molecules presents an additional dimension for tuning their intrinsic properties. Herein, we aim to tune the work function of 2D Ti3C2Tx by introducing ultrathin interlayers of organic dipoles (O.D.) with a defined dipole moment value. Interface engineering is achieved through the inclusion of poly(ethylene)amine (PEI 0.1 %) and third generation poly(amido-)amine (PAMAM G3), between the Ti3C2TX and c-Si. c-Si/O.D./Ti3C2Tx heterostructures were fabricated by simple drop casting of the aqueous MXene solution on O.D. coated c-Si substrates. Charge transport properties of the fabricated Schottky diodes with structure of c-Si/O.D./Ti3C2TX were evaluated through systematic analysis of the I-V and C-V characteristics. Our investigations reveal that diodes featuring O.D. as interlayers exhibit substantially reduced reverse saturation current density (J0) and enhanced built-in potential (Vbi). Work function of the fabricated c-Si/ MXene/O.D. structures were evaluated from the ultraviolet photo-emission spectroscopy (UPS) measurements. We report a significant reduction in the work function value of Ti3C2Tx from 5.8 eV to 4.2 eV for Ti3C2Tx/PEI 0.1 % and 3.3 eV for Ti3C2Tx/PAMAM-G3 heterostructures. Our study introduces an innovative approach for modifying the work function of Ti3C2Tx through the incorporation of O.D., highlighting the versatility of MXene electrodes to shape the future optoelectronic devices.

This work highlights the impact of growth temperature on electrical and optical properties of Al-doped ZnO (AZO) films deposited by atomic layer deposition (ALD) technique. The ALD process and super-cycle sequence have been optimized, identifying their influence on film resistivity. By using this optimum ALD procedure, the optical and electrical properties of AZO films have been widely analyzed considering the deposition temperature. Results show promising values with film resistivity in the range of 1 mΩcm and average optical absorption below 2% for 50 nm thick AZO layers. Hall effect, X-ray diffraction and ellipsometry measurements point out that these excellent values are related to their high carrier concentration and mobility, crystalline phase and optical band gap resulting in ALD AZO films with very good properties to be applied in photovoltaic devices as transparent conductive oxide electrode.

Low dimensional 2D materials such as graphene and carbon nano tubes have attracted significant attention from the solid-state device community and are considered as a potential candidate electrode to make functional contact with the Silicon (Si) and other industry compatible semiconductors. In this work we envisioned to utilize one such interesting 2D material Ti3C2Tx belonging to a rapidly emerging family of transition metal carbides/nitrides also known as MXene´s to fabricate the classical yet interesting Schottky junctions by simple drop casting of aqueous conducting colloidal solution of Ti3C2Tx on c-Si. Precisely, we anticipate to tune the work function of the Ti3C2Tx as well as the built-in potential of these Ti3C2Tx/c-Si Van der Waals heterojunction through inserting ultrathin interlayer of cationic polyelectrolytes/organic dipoles with a defined dipole moment value. In order to accomplish the interface engineering inclusion poly(ethylene)amine (PEI 0.1%), third generation poly(amido-)amine (PAMAM G3)), were tested between the Ti3C2TX and c-Si substrates. Charge transport properties of the fabricated Schottky devices with the structure of Ti3C2TX/organic dipole (O.D.) /c-Si were evaluated through systematic analysis of the current-voltage (I-V) and capacitance-voltage (C-V) results. I-V measurements under dark conditions revealed that Schottky diodes fabricated with the (PEI 0.1%) and PAMAM G3 interlayers exhibited lowest reverse saturation current density (J0) value and improved built in potential (Vbi) value as compared to the devices with only 2D-Ti3C2Tx as contact. We report reduction in the work function value of Ti3C2Tx from 5.8 eV to 4.2 eV for Ti3C2Tx/PEI (0.1%) and 3.3 eV for Ti3C2Tx/PAMAM G3 heterostructures. On the basis of the inferences drawn from the surface analysis we ascribe this reduction in work function value to the formation of interfacial dipoles at the Ti3C2Tx/O.D. interface. Importantly this study highlights an innovative method to tune the work function of the Ti3C2Tx MXene inclusion of organic dipoles as interlayers.

According to intermediate band (IB) theory, it is possible to increase the efficiency of a solar cell by boosting its ability to absorb low-energy photons. In this study, we used a hyperdoped semiconductor approach for this theory to create a proof of concept of different silicon-based IB solar cells. Preliminary results show an increase in the external quantum efficiency (EQE) in the silicon sub-bandgap region. This result points to sub-bandgap absorption in silicon having not only a direct application in solar cells but also in other areas such as infrared photodetectors. To establish the transport mechanisms in the hyperdoped semiconductors within a solar cell, we measured the J – V characteristic at different temperatures. We carried out the measurements in both dark and illuminated conditions. To explain the behavior of the measurements, we proposed a new model with three elements for the IB solar cell. This model is similar to the classic two-diodes solar cell model but it is necessary to include a new limiting current element in series with one of the diodes. The proposed model is also compatible with an impurity band formation within silicon bandgap. At high temperatures, the distance between the IB and the n-type amorphous silicon conduction band is close enough and both bands are contacted. As the temperature decreases, the distance between the bands increases and therefore this process becomes more limiting.

The synergism of heteroatom-doped carbon polyhedral with mixed-metal networks offers a myriad of electroactive sites that aid in excellent capacitive performance. Herein, a simple precipitation method was implemented to synthesis thiourea functionalized bimetallic ZIF-67 polyhedral as a sacrificial template, facilitating the construction of a superior N/S-carbon matrix with a Co-Ni-P (CNS/CNP) architecture through various thermal phosphorization processes. The CNS/CNP-2 revealed remarkable attributes after phosphorization at 500 degrees C, including a maximum specific capacitance of 588 F g-1 at a specific current of 1 A g-1 in 3 M KOH electrolyte. This outstanding performance arises from the synergy of N/S carbon matrix, which significantly increases electroactive sites and structural stability, and Co-Ni-P network, which enhances both redox-active site density and conductivity, facilitating rapid ion diffusion. Furthermore, an asymmetrical supercapacitor was integrated as CNS/CNP-2//AC and revealed a maximum specific energy and power of 30.3 W h kg- 1 and 12,489 W kg- 1, respectively, with capacitance retention of 90% even for 10,000 cycles. The ASC device was designed as a coincell to facilitate real-time applications. The study demonstrates that a synergistic effect between Co-Ni metal ions and a heteroatom matrix can yield an electrode material with a high specific capacity for energy storage devices.

Development of carrier selective contacts for crystalline silicon solar cells has been recently of great interest toward the further expansion of silicon photovoltaics. The use of new electron and hole selective layers has opened an array of possibilities due to the low‐cost processing and non‐doping contacts. Here, a non‐doped heterojunction silicon solar cell without the use of any intrinsic amorphous silicon is fabricated using Deoxyribonucleic acid (DNA) as the electron transport layer (ETL) and transition metal oxide V 2 O 5 as the hole transport layer (HTL). The deposition and characterization of the DNA films on crystalline silicon have been studied, the films have shown a n ‐type behavior with a work function of 3.42 eV and a contact resistance of 28 mΩ cm 2 . This non‐doped architecture has demonstrated a power conversion efficiency of 15.6%, which supposes an increase of more than 9% with respect to the cell not containing the biomolecule, thus paving the way for a future role of nucleic acids as ETLs.

In this work we study conjugated polyelectrolyte (CPE) films based on polyamidoamine (PAMAM) dendrimers of generations G1 and G3. These fractal macromolecules are compared to branched polyethylenimine (b-PEI) polymer using methanol as the solvent. All of these materials present a high density of amino groups, which protonated by methoxide counter-anions create strong dipolar interfaces. The vacuum level shift associated to these films on n-type silicon was 0.93 eV for b-PEI, 0.72 eV for PAMAM G1 and 1.07 eV for PAMAM G3. These surface potentials were enough to overcome Fermi level pinning, which is a typical limitation of aluminium contacts on n-type silicon. A specific contact resistance as low as 20 mΩ·cm2 was achieved with PAMAM G3, in agreement with the higher surface potential of this material. Good electron transport properties were also obtained for the other materials. Proof-of-concept silicon solar cells combining vanadium oxide as a hole-selective contact with these new electron transport layers have been fabricated and compared. The solar cell with PAMAM G3 surpassed 15% conversion efficiency with an overall increase of all the photovoltaic parameters. The performance of these devices correlates with compositional and nanostructural studies of the different CPE films. Particularly, a figure-of-merit (Vσ) for CPE films that considers the number of protonated amino groups per macromolecule has been introduced. The fractal geometry of dendrimers leads to a geometric increase in the number of amino groups per generation. Thus, investigation of dendrimer macromolecules seems a very good strategy to design CPE films with enhanced charge-carrier selectivity.

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 modification of 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.

In this work, a new design of transparent conductive electrode based on a graphene monolayer is evaluated. This hybrid electrode is incorporated into non-standard, high-efficiency crystalline silicon solar cells, where the conventional emitter is replaced by a MoOx selective contact. The device characterization reveals a clear electrical improvement when the graphene monolayer is placed as part of the electrode. The current–voltage characteristic of the solar cell with graphene shows an improved FF and Voc provided by the front electrode modification. Improved conductance values up to 5.5 mS are achieved for the graphene-based electrode, in comparison with 3 mS for bare ITO. In addition, the device efficiency improves by around 1.6% when graphene is incorporated on top. These results so far open the possibility of noticeably improving the contact technology of non-conventional photovoltaic technologies and further enhancing their performance.

Thermophotovoltaics has become a very attractive solution for heat-to-electricity conversion due to its excellent conversion efficiencies. However, further research is needed to reduce the device cost which is typically based on III-V semiconductors. To tackle this limitation, crystalline germanium (c-Ge) has been proposed as an excellent substrate for low-cost devices. One of the key advances behind high system efficiencies is the excellent reflec-tance of the out-of-band photons at the rear surface of the photovoltaic device. These photons with lower energy than the absorber bandgap are reflected back to the thermal emitter reducing its thermal losses. In this work, we explore the performance of hole selective contacts based on evaporated transition metal oxides (MoOx, VOx, WOx) to be introduced at the rear surface of c-Ge devices. Regarding electrical properties, we characterize the selectivity of the contact by measuring effective surface recombination velocity (Seff) and contact resistivity (rho C). Best results are obtained with MoOx contacted by Ag/ITO with Seff = 588 cm/s and rho C = 55.6 m omega cm2 which can be improved by using gold as a metal contact leading to Seff = 156 cm/s and rho C = 60.9 m omega cm2. Regarding out-of -band reflectance, it is better for the case of Ag/ITO/MoOx contact with 87.5% compared to 78.9% for Au/MoOx when a 1473 K black body spectrum is used. Device simulations show potential system efficiencies in the range of 18-19% which are comparable to the best reported efficiencies using c-Ge thermophotovoltaic devices.