Pn-junction Solar Cells Research Articles

Performance evaluation of 2D MoS2-based solar cells and realization of transparent ultra-thin devices

Molybdenum disulfide (MoS2) is an alternate absorber layer in 2D solar cells owing to its potential of proficient sunlight harvesting. The optimum electrical and optical properties of MoS2 validate it as a suitable photovoltaic absorber material. This work investigates the performance of 2D (and multi-layer) MoS2-based vertically stacked solar cell by numerical simulation process using one dimensional solar cell capacitance simulator (SCAPS). Two device configurations based on Schottky junction (ITO/n-MoS2/Au) and pn junction (ITO/n-MoS2/p-MoS2/Au) have been theoretically analyzed. The feasibility of ultra-thin transparent solar cells is also demonstrated, which is motivating from a technological outlook. Initially, the properties of the active layers are optimized to give the highest performance. The findings are explained on the basis of band alignment between the electrodes and the different layers. The potential barrier developed at the interface of different materials governs the output of the cells. The calculations forecast the material properties, which need to be tuned to fabricate solar cells with enhanced efficiency. After optimization, the highest efficiency obtained for single n-MoS2-based solar cell is 10.22%, while for the pn junction solar cell it is 16.86%. The optimized cells exhibit high open circuit voltages of ∼1.2 V, which is an essential factor for commercial realization of solar cells. Lastly, the performance of transparent solar cells based on thin 2D MoS2 films has been predicted which showcases the efficiency in the range of 0.78%–4.36%. These homo-junction device investigations of solely MoS2 layer along with employment of a strict control on the defects during deposition and fabrication of MoS2-based solar cells can ensure better performance of the device. Thus, it can open ways to develop next generation feasible solar cells with higher power density as compared to existing technology.

Study the influence of shell thickness in bimetallic Ag core&Au shell configurations integrated in bare Si PN junction solar cells

The effect of the gold layer thickness of Ag core&Au shell configurations on the performance of the bare Si n-type layer of a PN junction solar cell was explored. The different forms of Ag core&Au shell configurations were formed via pulsed laser ablation method of Ag and Au plate using second harmonic generation (SHG) of Nd:YAG laser wavelength at 530 nm with 0.61 J/cm2 energy flounce and various pluses repetition rate 350-500. The integrating of Ag core&Au shell configurations in n-type of bare PN Si junction was accomplished via pluses laser illumination of bare PN junction substrate. The photovoltaic results of formed solar cells showed strong dependence on Au shell thickness. Tangible enhancement was observed in the performance of bare Si solar cells after inserting core–shell configuration with specific shell thickness owning to the broadband absorption of plasmonics nanoparticles and the high values of specific surface area.

Cataloguing MoSi2N4 and WSi2N4 van der Waals Heterostructures: An Exceptional Material Platform for Excitonic Solar Cell Applications

Abstract2D materials van der Waals heterostructures (vdWHs) provide a revolutionary route toward high‐performance solar energy conversion devices beyond the conventional silicon‐based pn junction solar cells. Despite tremendous research progress accomplished in recent years, the searches of vdWHs with exceptional excitonic solar cell conversion efficiency and optical properties remain an open theoretical and experimental quest. Here, this study shows that the vdWH family composed of MoSi2N4 and WSi2N4 monolayers provides a compelling material platform for developing high‐performance ultrathin excitonic solar cells and photonics devices. Using first‐principle calculations, 51 types of MoSi2N4 and WSi2N4‐based [(Mo,W)Si2N4] vdWHs composed of various metallic, semimetallic, semiconducting, insulating, and topological 2D materials are constructed and classified. Intriguingly, MoSi2N4/(InSe, WSe2) are identified as Type II vdWHs with exceptional excitonic solar cell power conversion efficiency reaching well over 20%, which are competitive to state‐of‐the‐art silicon solar cells. The (Mo,W)Si2N4 vdWH family exhibits strong optical absorption in both the visible and UV regimes. Exceedingly large peak UV absorptions over 40%, approaching the maximum absorption limit of a freestanding 2D material, can be achieved in (Mo,W)Si2N4/α2‐(Mo,W)Ge2P4 vdWHs. The findings unravel the enormous potential of (Mo,W)Si2N4 vdWHs in designing ultimately compact excitonic solar cell device technology.

Open‐circuit voltage, fill factor, and heterojunction band offset in semiconductor diode solar cells

AbstractSemiconductor photovoltaics have been investigated for many years, and various materials and device architectures have been developed aiming for low cost and high efficiency. Despite the critical advances in the field, there are confusions in understanding such diode based solar cells, especially on open‐circuit voltage and fill factor. This review intends to provide a succinct summary and interpretation for the core elements that are related to a solar cell device. First, the fundamental concepts of PN junction and diode solar cell are introduced. Second, Fermi and quasi‐Fermi levels are described, followed by understanding open‐circuit voltage and fill factor. Thirdly, the effects of heterojunction band offset are discussed. In the end, a brief conclusion is presented.image

High conversion and quantum efficiency indium-rich p-InGaN/p-InGaN/n-InGaN solar cell

In this paper, an efficient three-layered p-In0.6Ga0.6N/p-In0.7Ga0.7N/n-In0.7Ga0.7N (PPN) solar cell was designed. The characteristics of the PPN-junction InGaN solar cell were simulated using the SCAPS-1D software. The effects of the thickness and carrier density of the PPN layer on solar cell performance were evaluated. The results were compared with those of the performance of the PN-junction solar cell. Results revealed that a thin top p-InGaN with a high carrier density had a considerable influence on the performance of the solar cell. Adding a p-InGaN layer as thin as 0.01 μm on the top of the PN-junction solar cell substantially improved the conversion efficiency of the solar cell from 21.39% (PN) to 30.23% (PPN).

Solar cells based on n+-AZO/p-BaSi2 heterojunction: Advanced opto-electrical modelling and experimental demonstration

We performed advanced opto-electrical simulations on thin-film BaSi 2 solar cells. First, absorption spectra of BaSi 2 - pn homojunction solar cells on Si substrate were calculated based on flat and/or pyramidally-textured surfaces, wherein 20-nm-thick n + -BaSi 2 was the topmost electron transport layer. By changing the front surface structure from flat to texture, the reflectance decreased in the wavelength ( λ ) range 700–1200 nm and the photocurrent density ( J ph ) delivered by the photogenerated carriers in the 500-nm thick p -BaSi 2 layer increased by 1.2 mA/cm 2 . Simulations revealed that the key factor inhibiting light absorption in the p -BaSi 2 layer was parasitic absorption in the n + -BaSi 2 and in the c-Si substrate. To solve these optical issues, we propose a new device structure, Al-doped n + -ZnO (AZO, 50 nm)/ i -ZnO (20 nm)/ p -BaSi 2 (500 nm) heterojunction solar cell (HJSC). In this device structure, the parasitic absorption reduced drastically, and J ph reached 30.23 mA/cm 2 . Furthermore, by replacing the Si substrate with a glass substrate, the light trapping worked more effectively, and the absorber layer thickness required for J ph to saturate was reduced to 1 μm, yielding 32.06 mA/cm 2 . Based on these simulation results, we manufactured n + -AZO/ p -BaSi 2 HJSC. The internal quantum efficiency exceeded 30% at λ = 600 nm, meaning that we demonstrated the operation of n + -AZO/ p -BaSi 2 HJSC for the first time. We investigated origins of small efficiencies compared to those simulated, and found that the passivation of defects in the p -BaSi 2 layer and the reduction of carrier recombination at the i -ZnO/ p -BaSi 2 interface would significantly improve the solar cell performance. This paper presents n + -AZO/p-BaSi 2 heterojunction solar cells (HJSC) to solve parasitic absorption in the n + -BaSi 2 and in the c-Si substrate of a BaSi 2 -pn homojunction solar cell. By replacing the Si substrate with a glass substrate, the light trapping works more effectively, and the absorber layer thickness required for photocurrent density to saturate can be reduced to 1 μm, yielding 32.06 mA/cm 2 . We manufactured n + -AZO/p-BaSi 2 HJSC, and demonstrated its operation for the first time. • We performed opto-electrical simulation on BaSi 2 pn-junction solar cells with flat and/or pyramidally-textured structure. • Parasitic absorption in the topmost layer significantly decreases the photocurrent density. • A new device structure, Al-doped n-ZnO/p-BaSi 2 , is proposed and demonstrated. • The importance of the carrier accumulation reduction at the ZnO/BaSi 2 interface is discussed.

Purely Protonic Solar Cells Fabricated from Photoacid-Modified Ion-Exchange Membranes

Analogies have been drawn between electronic semiconductors and water since 1956 when Fuller explained the similarity between silicon ionization, which generates an electron and a hole as mobile charge carriers, and water ionization, which yields a hydroxide and a proton as mobile charge carriers.1 Since then our group has taken steps to produce a water-based pn-junction solar cell that uses water as a protonic semiconductor. Toward this, we have demonstrated photovoltaic action using photoacid-modified Nafion membranes alone2 and when laminated to an anion-exchange membrane,3 yet each demonstration required the membrane to be wetted by an aqueous acid–base gradient. In this report, a liquid-electrolyte-free photoacid-modified ion-exchange membrane–electrode–assembly (MEA) driving reversible H2 redox chemistry is described. The cell architecture consists of a three-layer membrane (cation-selective Nafion membrane, aminopyrene-functionalized polyphenylene oxide, anion-selective X37 membrane) that was characterized using direct membrane contacts consisting of platinized platinum mesh. The MEA achieved V oc = 10 mV and J sc = 7.5 μA/cm2 under low-intensity 405 nm illumination, resulting in an internal quantum efficiency of ~0.2%. The reported composite MEA overcomes the problem of co-ion crossover by eliminating co-ions altogether while still exhibiting photovoltaic action due to the charge-separating potential across the membrane interfaces. Because photovoltaic performance persists in the absence of electrolyte gradients and because the potentiometric measurements conducted here are only sensitive to the electrochemical potential of protons, we can conclude that the light-induced voltage and current originate from protons and/or hydroxides, and no other ionic species. This MEA thus serves as a robust proof-of-concept of water’s role as a protonic semiconductor. It also offers a promising format for fundamental studies on the origin of photovoltaic action in photoacid–polymer-electrolyte membranes in the absence of the convoluting effects of liquid electrolyte. Acknowledgments: This work was supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Early Career Research Award under award number DE-SC0019162 from the Solar Photochemistry Program. Fuller, C. S. Chem. Prog. 1956, 17, 75-93.White, W.; Sanborn, C. D.; Reiter, R. S.; Fabian, D. M.; Ardo, S. J. Am. Chem. Soc. 2017, 139, 11726–11733.White, W.; Sanborn, C. D.; Fabian, D. M.; Ardo, S. Joule 2018, 2, 94-109.

A promising concept to push efficiency of pn-junction photovoltaic solar cell beyond Shockley and Queisser limit based on impact ionization due to high electric field

This paper studies the implication of impact ionization due to a high electric field on the improvement of the photovoltaic solar cell efficiency. A high electric field existing in the space charge region (SCR) of the solar cell induces the generation of additional free carriers by accelerating the photogenerated electron-hole pairs which collide with the lattice of the semiconductor material. The resultant current taking into account this carriers’ multiplication (CM) is calculated and the maximum efficiency of the photovoltaic solar cell is evaluated. The found results show that CM in photovoltaic solar cell occurs in a definite range of the electric field near to the pn-junction and could improve significantly his efficiency for more than 5% at an electric field less than 4 × 105 V/cm, depending on the width of the space charge region or the multiplication region. The usable range of the electric field for CM in solar cell is linked to the type of semiconductor material used.

Investigation of Rbx(MA)1−xPbI3(x = 0, 0.1, 0.3, 0.5, 0.75, 1) perovskites as a potential source of P- and N-type materials for PN-junction solar cell

We report the investigation of monovalent cation rubidium (Rb+)-doped methylammonium lead iodide (CH3NH3PbI3; MAPbI3; CH3NH3=MA)-based perovskites. The perovskite MAPbI3 have large absorber coefficient than silicon and gallium arsenide, long carrier life, and optimal bandgap, low exciton binding energy, and low manufacturing cost make this material ideal for photovoltaic applications. However, material stability is prime concern and major limitation towards the commercialization of perovskite solar cell. The organic part, i.e., MA, is volatile and subject to degradation in humid/oxygen environment. Here, an effort is made to replace the organic part in MAPbI3 with oxidation stable Rb cation. The Rbx(MA)1−xPbI3 (x = 0–1) materials were synthesized by solution process method followed by thin-film deposition. The post-deposition annealing of all Rbx(MA)1−xPbI3 (x = 0–1) films is carried out at optimized temperature of 100 °C in argon-filled glove box. The pristine MAPbI3 films have shown tetragonal structure, whereas orthorhombic distortion is observed in all Rb-doped samples. The electron micrographs of doped films have shown dendritic structures which converted into a beautiful thread/wire like structures in all inorganic RbPbI3 films. Optical studies also show phase transition in Rb-doped samples in two different regions. The absorption intensity observed by photoluminescence studies is increased by six orders of magnitude in partially doped samples. It is observed that the carrier concentration and mobility of the material can be controlled and the conductivity type of the material could be tuned from n-type to p-type by doping with Rb doping. The X-ray photoemission spectroscopy (XPS) showed the oxidation states of Pb and I are + 2 and − 1 in all samples. The intercalation of inadvertent carbon and oxygen in Rbx(MA)1−xPbI3 films was also investigated by XPS. It is observed that respective oxygen and carbon-related peaks responsible for decomposition of MAPbI3 material decrease in intensity in all partially doped samples, showing the stability of the material by introducing oxidation stable Rb. This study also opens a way to the future study of perovskite solar cells with perovskite film as a P–N junction. These partially doped perovskites with enhanced stability and improved optoelectronic properties could be an attractive candidate as light harvesters for photovoltaic device application.

MEH-PPV/CdS Hybrid Nanowire Polymer Solar Cell Array

One-dimensional ordered hybrid pn-junction solar cell devices of poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) and cadmium sulphide (CdS) were fabricated. CdS nanowires were synthesized with alumina membrane by using potentiostatic electrodeposition. The CdS nanowire template was dissolved in sodium hydroxide to obtain the vertically aligned nanowires. The solar cell devices were characterized to study the optical, morphological and optoelectronic properties. The absorption curve revealed that the CdS nanowire and MEH-PPV have complementary absorption spectra leading to an increase in the absorption intensity for the composite system. The photoluminescence peaks of CdS nanowires were found to be quenched because of the overlapping between polymer absorption and CdS emission. The devices characterized under illumination condition at input intensity, 100 mW/cm2 showed short circuit current density, open circuit voltage, fill factor and power conversion efficiency ~ 16 mA/cm2, 660 mV, 50% and 3.9%, respectively.

Electrochemical deposition of Cu-doped p-type iron oxide thin films

Fe2O3 and γ-FeOOH, major constituents of iron rust, are n-type semiconductors with a bandgap of 2.0 ∼ 2.6 eV. In this work, we deposited Cu-doped p-type iron oxide by the electrochemical deposition method. p-type iron oxide is expected to be applied for photo-cathodes in electrochemistry and also for pn junction solar cells. The films were deposited from an aqueous solution containing FeSO4 and CuSO4 and annealed in air at 400 °C. The conduction type was converted into p-type when the ratio of copper to iron in the film was about 10% or more. Annealing in air improved film adhesion to the substrate and enhanced p-type conductivity.

Heterovalent doping and energy level tuning in Ag2S thin-films through solution approach: pn-Junction solar cells

In this work, we have fabricated heterojunction solar cells between layers of p-type CuS and n-type Ag2S deposited through successive ionic layer adsorption and reaction (SILAR) method. We have introduced Sn2+ and Al3+ as heterovalent-dopants in the cationic sites of Ag2S and studied their effect on the photovoltaic performance of the heterojunctions. As evidenced from the band diagrams drawn from scanning tunneling spectroscopy (STS) of the components, such doping shifted the Fermi energy of pristine Ag2S towards the conduction band-edge influencing the solar cell activities of the heterojunction in turn. While the trivalent Al-dopants introduced defects states in Ag2S and hence deteriorated the cell efficiency, doping with 5 at% of Sn at the silver site resulted in band-engineered pn-junction solar cells with a power conversion efficiency of 2.85%.

A solution approach to p-type Cu2FeSnS4 thin-films and pn-junction solar cells: Role of electron selective materials on their performance

We present formation of Cu2FeSnS4 (CFTS) thin-films through successive ionic layer adsorption and reaction (SILAR) method. We have considered a range of chalcogenides as n-type compound semiconductors, also formed through SILAR method, in conjunction with the p-nature of CFTS to fabricate and characterize pn-junction solar cells. The film-deposition method, which is a low temperature and non-vacuum one and is also suitable for obtaining films of large-areas, has maintained a balance between fabrication cost and phase purity. From scanning tunneling spectroscopy and correspondingly density of states of the semiconductors, we have estimated their band-edges to draw energy-level diagram of the devices. This has led in establishing a correlation between the band-alignment in the pn-junctions and energy conversion efficiency of solar cells based on the junctions. The correlation has been further supported by diode parameters of the junctions. An energy conversion efficiency of 2.9% with promising reproducibility could be achieved in CFTS|Bi2S3 junctions formed through this room-temperature film deposition route.

Optimization of hybrid organic/inorganic poly(3-hexylthiophene-2,5-diyl)/silicon solar cells

In the last years, hybrid organic/silicon solar cells have attracted great interest in photovoltaic research due to their potential to become a low-cost alternative for the conventionally used silicon pn-junction solar cells. This work is focused on hybrid solar cells based on the polymer poly(3-hexylthiophene-2,5-diyl), which was deposited on n-doped crystalline silicon via spin-coating under ambient conditions. By employing an anisotropic etching step with potassium hydroxide (KOH), the reflection losses at the silicon surface were reduced. Hereby, the short-circuit current density of the hybrid devices was increased by 31%, leading to a maximum power conversion efficiency (PCE) of 13.1% compared to a PCE of 10.7% for the devices without KOH etching. In addition, the contacts were improved by replacing gold with the more conductive silver as top grid material to reduce the contact resistance and by introducing a thin (∼0.5 nm) lithium fluoride layer between the silicon and the aluminum backside contact to improve electron collection and hole blocking. Hereby, the open-circuit voltage and the fill factor of the hybrid solar cells were further improved and devices with very high PCE up to 14.2% have been realized.

Hydrodynamic modeling of hot-carrier effects in a PN junction solar cell

This article presents a one-dimensional two-temperature hydrodynamic model to study the thermal and electrical behavior of a gallium arsenide (GaAs) PN junction solar cell. This model treats both electron and heat transfer on equal footing and includes Gauss’s law, continuity and momentum equations for electrons and holes, and energy balance using temperature for both carriers and lattice. A zero-order system of equations is obtained using asymptotic series expansions based on the electron Reynolds number for steady-state conditions. An iterative scheme is implemented to solve the zero-order system. The results show the influence of carriers and lattice temperatures in the electrical performance of a GaAs PN junction solar cell. Higher values of power output are obtained with low lattice temperature and hot energy carriers. This modeling contributes to improve the thermal control in photovoltaic technologies.

Dye-Sensitized Solar Cell with Electrophoretic Deposited Photocatalytic Carbon Nanotube Counter Electrode: Nanotube Density and Cell Performance

Prospective solar cell technologies such as dye-sensitized solar cells (DSSCs), organic photovoltaics (OPVs) and much recently discovered perovskite solar cells compared to the conventional solid-state pn-junction type silicon solar cells are of high demand for solar energy conversion due to their simple fabrication processes, high energy conversion efficiency, low cost, and potential for flexible solar panels1-4. Among the emerging solar cell technologies, DSSC’s stability and reliability in air is so far most promising compared to OPVs and perovskite cells. While platinum film is used as photocatalyst in the counter electrode of a conventional DSSC, nanostructured alternatives such as carbon nanotubes (CNTs) can further decrease both material and fabrication cost, enhance mechanical flexibility and provide comparable performances5-6. Network of metallic CNTs have demonstrated significant potential for alternate transparent conductors to indium doped tin oxide (ITO). Moreover, its catalytic activity for DSSC counter electrode has also been previously explored to replace platinum7. However, a lower conversion efficiency still persists. Placing the nanotube on counter electrode in a network structure with optimal density is therefore desired for enhances solar cell performance, as the rate of charge transfer reaction on the counter electrode and hence the photo-conversion efficiency is dependent on optimal density of nanotubes. While enormous density of nanotubes in counter electrode can provide large amount of catalytic surface for the I-/I3 -reduction reaction, high nanotube density can be an obstacle for fast charge transport. On the other hand, a sparse nanotube network might provide just enough catalytic surfaces without barricading charge transport. The sparse network also has high light transmittance to build transparent solar cells and solar panels. In this work, we report an electrophoretic deposition of CNT network on to fluorine-doped tin oxide (FTO) glass substrates. We fabricated DSSCs using these CNT-decorated-electrodes as counter electrodes and tested the cells to evaluate their photocatalytic activities using a solar simulator. We have demonstrated optimal CNTs electrophoretic deposited onto the FTO surface (30-45 seconds deposition at a DC bias of 40V) with conversion efficiency comparable to a DSSC with platinum counter electrode. This work demonstrates the efficient use of catalytic CNTs with optimal density for building DSSCs. [1] B. O’Regan and M. Grätzel, Nature 353 (1991) 737 [2] A. Hagfeldt et al., Chem. Rev. 110 (2010) 6595 [3] M. Gratzel, J. Photochemistry and Photobiology C: Photochemistry Reviews 4 (2003) 145 [4] T. Miyazaki, A. Akisawa, and T. Kashiwagi, Renewable Energy 30 (2005) 281 [5] P. Joshi et al., Energy Environ. Sci., 2 (2009), 426-429 [6] E. Ramasamy et al., Appl. Phys. Lett. 90 (2007) 173103 [7] K. Suzuki et al., Chem. Lett. 32 (2003) 28; J. –G. Park et al., Electrochimica Acta 85 (2012) 600 Figure 1

Study of the Electrical Properties and the Internal Quantum Efficiency of SnO2-p/n- Si Thin Film Solar Cells

SnO2-p/n-Si thin film solar cells were prepared by a vacuum evaporation technique, and SnO2 studied as a transparent antireflection coating with the n-type sili- con wafer to fabricate a thin film. The oxidation of the Si surface takes place simultaneously with the evaporation process. Dark forward and reverse I-V characteristics for the SnO2-p/n-Si structure in the temperature range (25- 300 ◦ C), for a thickness of 5000 u A are measured. The illuminated current-voltage characteristics of a PN junction solar cell have been investigated. The capacitance-voltage (C-V) measurements at room temperature are carried out to show the variation of capacitance with frequency. The rela- tive IQE for the fabricated SnO2-p/n-Si structure with 5000 u A thickness at 300 ◦ C are calculated. The fabricated struc- ture has a maximum response at a wavelength in the range, 0.8-1.05μm.

Plasmonic effect in pn-junction solar cells based on layers of semiconductor nanocrystals: Where to introduce metal nanoparticles?

We have introduced metal nanoparticles in pn-junction solar cells to study plasmonic effect in such devices. Here, the junction was based on a layer of copper–zinc–tin–sulfide (CZTS) nanocrystals as a p-type semiconductor and another layer of copper-diffused silver indium disulfide (Cu@AgInS2) nanocrystals as an n-type material in sequence. We introduced silver nanoparticles at different locations of pn- and also of np-junctions: (i) in the p-layer, (ii) in the n-layer, (iii) in both the layers, and (iv) at the interface between the layers of p- and n-type nanocrystals. The results in both pn- and np-junctions show that the devices with metal nanoparticles in p-type layer evidenced a substantial increase in energy conversion efficiency of solar cells as compared to other devices and the control device without any silver nanoparticles. We have inferred that the presence of silver nanoparticles in the depletion layer might have narrowed down the width of the region; metal nanoparticles in the n-layer acted as electron-traps to localize them hindering electron-transport and thereby reducing the efficiency of such plasmonic solar cells. Our results have shown that while introducing metal nanoparticles in solar cells, they should be placed only in the p-layer so that transport of electrons in plasmonic solar cells remains unaffected.

Analysis of the electrical properties of Cr/n-BaSi2 Schottky junction and n-BaSi2/p-Si heterojunction diodes for solar cell applications

Current status and future prospects towards BaSi2 pn junction solar cells are presented. As a preliminary step toward the formation of BaSi2 homojunction diodes, diodes with a Cr/n-BaSi2 Schottky junction and an n-BaSi2/p-Si hetero-junction have been fabricated to investigate the electrical properties of the n-BaSi2. Clear rectifying properties were observed in the current density versus voltage characteristics in both diodes. From the capacitance-voltage measurements, the build-in potential, VD, was 0.53 V in the Cr/n-BaSi2 Schottky junction diode, and the Schottky barrier height was 0.73 eV calculated from the thermoionic emission theory; the VD was about 1.5 V in the n-BaSi2/p-Si hetero-junction diode, which was consistent with the difference in the Fermi level between the n-BaSi2 and the p-Si.

Interface investigation of planar hybrid n-Si/PEDOT:PSS solar cells with open circuit voltages up to 645 mV and efficiencies of 12.6 %

We have studied interface formation properties of hybrid n-Si/PEDOT:PSS solar cells on planar substrates by varying the silicon substrate doping concentration (N D). Final power conversion efficiencies (PCE) of 12.6 % and open circuit voltages (V oc) comparable to conventional diffused emitter pn junction solar cells have been achieved. It was observed, that an increase of N D leads to an increase of V oc with a maximal value of 645 mV, which is, to our knowledge, the highest reported value for n-Si/PEDOT:PSS interfaces. The dependence of the solar cell characteristics on N D is analyzed and similarities to minority charge carrier drift-diffusion limited solar cells are presented. The results point out the potential of hybrid n-Si/PEDOT:PSS interfaces to fabricate high performance opto-electronic devices with cost-effective fabrication technologies.