High Contact Resistance Research Articles

Investigation on the physical and electrochemical properties of typical Ni-based alloys used for the bipolar plates of proton exchange membrane fuel cells

The phase, mechanical properties, corrosion resistance, hydrophobicity, and interface contact resistance of three typical Ni-based alloys (Hastelloy B, Hastelloy C-276, and Monel 400) and 304 stainless steels were experimentally studied to evaluate their service performances as bipolar plate materials of proton exchange membrane fuel cells. All four alloys exhibit single-phase face-centered cubic structure, high strength, good ductility, and high hardness. Hastelloy C-276 has the best ductility with an uniform elongation of 72.5% and highest hardness of 363.7 HV. Hastelloy B has the highest ultimate tensile strength of 913.6 MPa. The hydrophobicity of all four alloys is not good, although Monel 400 has the highest water contact angle of 84.2°. Hastelloy B, Hastelloy C-276, and 304 stainless steel exhibit unsatisfying corrosion resistance in a simulated acidic work environment of proton exchange membrane fuel cell (0.5 M H2SO4+2 ppm HF, 80 °C, H2) and high interface contact resistance. By contrast, Monel 400 demonstrates excellent corrosion resistance with a corrosion current density of 5.9 × 10−7 A cm−2 and a low interface contact resistance of 7.2 mΩ cm2 at 140 N/cm2. In terms of comprehensive performance, Monel 400 is the best uncoated material for the bipolar plates of proton exchange membrane fuel cells among typical Ni-based alloys.

Highly Stable Metal─Na0.02Pb0.98Te Contacts for Medium Temperature Thermoelectric Devices.

In the medium temperature (600-850 K) range, Na0.02Pb0.98Te is a highly efficient p-type thermoelectric compound. Device fabrication utilizing this compound for power generation demands highly stable low-contact resistance contacts with metal electrodes. This work investigates the microstructural, electrical, mechanical, and thermochemical stability of Na0.02Pb0.98Te-metal (Ni, Fe, and Co) contacts made by a one-step vacuum hot pressing process. Direct contact mostly resulted in either an interface with poor mechanical integrity, as in Co and Fe, or poisoning of the TE compound, as in the case of Ni, which results in high specific contact resistance (rc). In Ni and Co, adding a SnTe interlayer lowers the rc and strengthens the contact. It does not, however, effectively stop Ni from diffusing into Na0.02Pb0.98Te. The bonding is poor in the Fe/SnTe/Na0.02Pb0.98Te contacts due to the absence of any reaction at the Fe/SnTe interface. A composite buffer layer Co + 75 vol % SnTe with SnTe improves the mechanical stability of the Co contact with moderately lesser rc than pure SnTe alone. However, a similar approach with Fe does not yield stable contact. The Co/Co + 75 vol % SnTe/SnTe/Na0.02Pb0.98Te contact exhibits rc less than 50 μΩ cm2 and has good microstructural and mechanical stability after annealing at 723 K for 170 h.

Largely Reducing the Contact Resistance of Molybdenum Ditelluride by In Situ Potassium Modification

AbstractSemiconducting molybdenum ditelluride (MoTe2) is widely reported owing to its favorable electronic and optoelectronic properties. The effective modulation of its electrical characteristics has garnered growing attention in regard to building high‐performance MoTe2‐based complementary devices. However, the inherent Schottky barrier (SB) in MoTe2‐based devices severely inhibits the charge‐carrier injection efficiency, leading to a high contact resistance between MoTe2 and contact metals. Here, an efficient method is presented for reducing the SB height of field‐effect transistors (FETs) based on MoTe2 by in situ potassium modification. Interestingly, the electrons transported from K continuously change the electrical characteristics of MoTe2 FET from ambipolar to n‐type with an improvement of electron mobility of over one order of magnitude. Meanwhile, the contact resistance of MoTe2 FET is significantly decreased from 11.5 to 0.4 kΩ µm. By regulating the modification region spatially, it is possible to create a complementary inverter with a high gain of ≈32 at VDD = 3 V. This research demonstrates a relatively simple method for optimizing the contact for MoTe2‐based devices and tuning the electrical properties of MoTe2 for future high‐performance complementary electronics.

High‐performance, coplanar amorphous InGaZnO thin‐film transistors by spray pyrolysis on polyimide substrate for low‐cost manufacturing of foldable active‐matrix organic light emitting diode display

AbstractWe report a method for low‐cost deposition of bubble‐free, high‐quality amorphous InGaZnO (a‐IGZO) on polyimide (PI) substrate for foldable active‐matrix organic light emitting diode (AMOLED) display by spray pyrolysis. The coplanar thin‐film transistor (TFT) with spray‐pyrolyzed (SP) a‐IGZO on PI substrate exhibits threshold voltage (VTH) of −0.8 V, saturation mobility of 40.95 cm2 V−1 s−1, and subthreshold swing of 0.18 V per decade with on/off drain current ratio of ~108. The high mobility TFT could be achieved using high substrate temperature (350°C) and low contact resistance by NF3 plasma on the SP a‐IGZO. The TFT shows a ΔVTH of −0.4 V when it is bent on a cylinder of 1‐mm radius. The TFT shows the ΔVTH of +0.05 V for positive bias temperature stress at +20 V at 60°C for 1 h. The ring oscillator made of a‐IGZO TFTs exhibits an oscillation frequency of 2.38 MHz at VDD of 10 V with a propagation delay of 9.13 ns per stage. Therefore, the a‐IGZO TFT by spray pyrolysis could be used for low‐cost, high‐performance, and flexible display TFT backplane.

Novel synthesis of polyaniline, manganese oxide and nickel sulfide lavandula-like composites as efficient active material of supercapacitor

Transition metal sulfides (TMS) are considered as the efficient battery-type material due to high theoretical capacity, redox reversibility, and electrical conductivities. The Ni3S2 with a high theoretical capacity and abundant sources is one of the efficient energy storage materials, but high contact resistances and poor cyclic stability of Ni3S2 restrict its electrochemical performance. The binder-free design, morphology regulation, composite development, and conductive polymer incorporation are useful strategies for solving the problems of Ni3S2. In this study, a novel lavandula-like manganese oxide, Ni3S2 and polyaniline composite (PANI/MnOx/Ni3S2) is synthesized on Ni foam as the binder-free battery-type electrode of battery supercapacitor hybrid (BSH) as clean energy sources at the first time. The Mn amounts and aniline electropolymerization durations play important roles on active sites and electrical conductivity. The functions of MnOx and PANI are analyzed by comparing physical and electrochemical properties of Ni3S2, MnOx/Ni3S2, PANI, PANI/Ni3S2 and PANI/MnOx/Ni3S2 electrodes. The largest specific capacitance (CF) of 9.5 F/cm2 at 30 mA/cm2 is achieved for the optimized PANI/MnOx/Ni3S2 electrode. A BSH assembled using activated carbon and PANI/MnOx/Ni3S2 electrodes presents the maximum energy density of 2.31 Wh/m2 at 65 W/m2, and the CF retention of 78.5 % and Coulombic efficiency of 95.8 % after 10,000 times repeatedly charging and discharging process.

Minimization of the electrical contact resistance in thin-film thermoelectric device

High electrical contact resistance refrains the performance of thin-film thermoelectric devices at the demonstrative level. Here, an additional Ti contact layer is developed to minimize the electrical contact resistance to ∼4.8 Ω in an as-assembled thin-film device with 50 pairs of p–n junctions. A detailed interface characterization demonstrates that the low electrical contact resistance should be mainly attributed to the partial epitaxial growth of Bi2Te3-based thin-film materials. Correspondingly, the superlow electrical contact resistance facilitates the applicability of the out-of-plane thin-film device and results in an ultrahigh surface output power density of ∼81 μW cm−2 at a low temperature difference of 5 K. This study illustrates the Ti contact layer that strengthens the contact between Cu electrodes and Bi2Te3-based thermoelectric thin films mainly through partial epitaxial growth and contributes to high-performance thin-film thermoelectric devices.

Ohmic Behavior in Metal Contacts to n/p-Type Transition-Metal Dichalcogenides: Schottky versus Tunneling Barrier Trade-off

High contact resistance (RC) between 3D metallic conductors and single-layer 2D semiconductors poses major challenges toward their integration in nanoscale electronic devices. While in experiments the large RC values can be partly due to defects, ab initio simulations suggest that, even in defect-free structures, the interaction between metal and semiconductor orbitals can induce gap states that pin the Fermi level in the semiconductor band gap, increase the Schottky barrier height (SBH), and thus degrade the contact resistance. In this paper, we investigate, by using an in-house-developed ab initio transport methodology that combines density functional theory and nonequilibrium Green’s function (NEGF) transport calculations, the physical properties and electrical resistance of several options for n-type top metal contacts to monolayer MoS2, even in the presence of buffer layers, and for p-type contacts to monolayer WSe2. The delicate interplay between the SBH and tunneling barrier thickness is quantitatively analyzed, confirming the excellent properties of the Bi–MoS2 system as an n-type ohmic contact. Moreover, simulation results supported by literature experiments suggest that the Au–WSe2 system is a promising candidate for p-type ohmic contacts. Finally, our analysis also reveals that a small modulation of a few angstroms of the distance between the (semi)metal and the transition-metal dichalcogenide (TMD) leads to large variations of RC. This could help to explain the scattering of RC values experimentally reported in the literature because different metal deposition techniques can result in small changes of the metal-to-TMD distance besides affecting the density of possible defects.

Liquid Metal Based Low Resistance Interconnect Technology

There is an increasing desire for interconnect technologies that provide low contact resistance, shorter electrical path and enable pin count scaling without the need for complex loading mechanisms. Ball grid array (BGA) technologies provide some of these benefits but add the complexity of surface mount challenges, especially on large form factor packages. Furthermore, customers value the flexibility of late and separable attach capability that sockets provide. Sockets, however come with a higher contact resistance and the required compression force drives significant cost and complexity to the loading mechanism. A liquid metal-based socket interconnect technology is introduced that offers BGA like performance with the benefits of a traditional socket. The liquid metal being studied is a gallium based eutectic alloy with a low melting point. The measured contact resistance is the lowest amongst available socket technologies and is equivalent to a permanently soldered down connection. The paper describes a process to manufacture a liquid metal interconnect and electrical characteristics of such an interconnect. This technology is in its infancy with insufficient data on field reliability risks or potential failure mechanisms when used as an interconnect. However, traditional evaluation techniques are less relevant for this novel interconnect and new methodologies are introduced to evaluate this technology.

Improvement in Corrosion Resistance and Interfacial Contact Resistance Properties of 316L Stainless Steel by Coating with Cr, Ti Co-Doped Amorphous Carbon Films in the Environment of the PEMFCs.

In order to obtain films with high corrosion resistance and excellent interfacial contact resistance (ICR) on 316L stainless steel used for bipolar plates in proton-exchange membrane fuel cells (PEMFCs), Cr, Ti co-doped amorphous carbon films were prepared on 316L stainless steel. The preparation method for the coating was magnetron sputtering. The doping amount of the Ti element was controlled by a Cr target and a Ti target current. The change in the structure and properties of the coating after the change from Cr single-element doping to Cr and Ti co-doping was studied. The change rule of the structure and properties of the coating from Cr single-element doping to Cr and Ti co-doping was studied. An increase in the Ti content led to a decreased grain boundary, a flatter surface, and a higher sp2-hybridized carbon content. TiC and CrC nanocrystals were formed in the amorphous carbon structure together. The amorphous carbon films doped with Cr and Ti simultaneously achieved a low ICR and high corrosion resistance compared with single-Cr-doped amorphous carbon. The enhanced corrosion resistance was attributed to the decreasing grain boundary, the formation of the TiC crystal structure, and the smaller grain size. The best performance was obtained at a Ti target current of 2A. Compared with bare 316L stainless steel, the corrosion resistance of Cr, Ti co-doped amorphous carbon (Icorr = 5.7 × 10-8 A/cm2, Ti-2 sample) was greatly improved. Because Ti doping increased the content of sp2-hybridized carbon in the coating, the contact resistance of the coating decreased. Moreover, the interfacial contact resistance was 3.1 mΩ·cm2 in the Ti-2 sample, much lower than that of bare 316L stainless steel. After the potentiostatic polarization test, the coating still had excellent conductivity.

Bi-polysilicon passivating contact technique for crystalline silicon solar cell

Polysilicon (poly-Si) passivating contacts overcome the direct metal–semiconductor contact drawback of traditional industrial crystalline silicon (c-Si) solar cells by inserting a layer stack of poly-Si and silicon oxide layers at the rear full-area metal/c-Si interface, which is well-known as a tunnel oxide passivating contact (TOPCon). In conventional industrial TOPCon devices, the direct contact problem affects the emitter, which deteriorates the passivation quality and suppresses the open-circuit voltage (Voc). We herein introduce an innovative bi-poly-Si technique (Bi-TOPCon) featuring rear full-area passivated poly-Si and emitter locally passivated poly-Si to improve the passivation quality of the TOPCon device. The local emitter poly-Si is introduced using metal mask alignment, and its properties are optimised toward high passivation quality and low contact resistance. The Bi-TOPCon device shows a significant improvement in Voc (Voc > 700 mV). Bi-TOPCon is a promising technology for high-efficiency, next-generation industrial TOPCon devices.

Advances of sulfide‐type solid‐state batteries with negative electrodes: Progress and perspectives

AbstractAll‐solid‐state battery (ASSB) technology is the focus of considerable interest owing to their safety and the fact that their high energy density meets the requirements of emerging battery applications, such as electric vehicles and energy storage systems (ESSs). In light of this, current research on high‐energy ASSBs harnesses the benefits of solid‐state battery systems by employing anode materials with high energy densities. Owing to the excellent physical safety of solid electrolytes, it is possible to build a battery with high energy density by using high‐energy negative electrode materials and decreasing the amount of electrolyte in the battery system. Sulfide‐based ASSBs with high ionic conductivity and low physical contact resistance is recently receiving considerable attention. This review provides a summary on various anode materials for ASSBs operating under electrochemically reducing conditions from the perspective of electrochemical and physical safety. The electrochemical and physical properties of sulfide electrolytes used for lithium (Li) metal and particle‐type anode materials are presented, as well as strategies for mitigating interfacial failures in solid‐state cells through interlayer and electrode design.image

Semimetal–Monolayer Transition Metal Dichalcogenides Photodetectors for Wafer‐Scale Broadband Photonics

Atomically thin 2D transition metal dichalcogenides (TMDs), such as MoS2, are promising candidates for nanoscale photonics because of strong light–matter interactions. However, Fermi‐level pinning due to metal‐induced gap states (MIGS) at the metal–monolayer (1L)‐MoS2 interface limits the application of optoelectronic devices based on conventional metals due to high contact resistance. On the other hand, a semimetal–TMD–semimetal device can overcome this limitation, where the MIGS are sufficiently suppressed allowing ohmic contacts. Herein, the optoelectronic performance of a bismuth–1L‐MoS2–bismuth device with ohmic electrical contacts and extraordinary optoelectronic properties is demonstrated. To address the wafer‐scale production, full coverage 1L‐MoS2 grown by chemical vapor deposition. High photoresponsivity of 300 A W−1 at wavelength 400 nm measured at 77 K, which translates into an external quantum efficiency (EQE) ≈1000 or 105%, is measured. The 90% rise time of the devices at 77 K is 0.1 ms, suggesting they can operate at the speed of ≈10 kHz. High‐performance broadband photodetector with spectral coverage ranging from 380 to 1000 nm is demonstrated. The combination of large‐array device fabrication, high sensitivity, and high‐speed response offers great potential for applications in photonics, including integrated optoelectronic circuits.

Prevention of Carbon Corrosion by TiC Formation on Ti Current Collector in Seawater Batteries

AbstractSeawater batteries (SWBs) are a type of sodium‐air batteries that use abundant seawater as the source of the catholyte. A cathode current collector in traditional SWBs is composed of titanium (Ti) and carbon‐based current collectors. The high contact resistance between Ti and carbon‐based current collectors as well as the slow kinetics of oxygen evolution and reduction reactions increase the overpotential, resulting in side reactions such as carbon corrosion. To enhance the performance of SWBs, previous studies have focused on carbon current collectors, catalysts, and polymer binders, while ignoring the importance of Ti. In this study, a facile carbon diffusion technique is employed to successfully form titanium carbide (TiC) on the surface of Ti. SWBs with engineered Ti demonstrate considerably improved performance (four times higher cycling stability, 30% increased power performance, 40% reduced voltage gap) in relation to those with pristine Ti. This significantly improved electrochemical performance is found to be attributable to the prevention of carbon corrosion due to i) the reduction of contact resistance (owing to rough TiC surface) and ii) the electrocatalytic effect of TiC. Finally, engineered Ti is applied to large‐area SWBs and its potential applicability in energy storage systems is confirmed.

Sb2Te3/MoS2 Van der Waals Junctions with High Thermal Stability and Low Contact Resistance

AbstractTwo‐dimensional transition metal dichalcogenides (TMDCs) demonstrate great potential in nanoelectronics devices owing to their high carrier mobility in the atomically thin channel regime. However, high contact resistance between source/drain electrodes and TMDC channels hinders the TMDCs applications in the very‐large‐scale integration (VLSI) field. Here, this work reports atomically aligned van der Waals (vdW) junction fabrications through thermal‐induced crystallization of layered Sb2Te3 electrodes on monolayer MoS2 using VLSI‐compatible physical vapor deposition and annealing processes. Due to Fermi‐level unpinning with a small band offset between Sb2Te3 and MoS2 and small density of state of Sb2Te3, better device performance is demonstrated on MoS2 MOSFETs with Sb2Te3/W contact than that of Sb/W contact. Moreover, the ideal vdW junctions are found to demonstrate extreme high‐thermal robustness. No intermixing at the Sb2Te3/MoS2 interface or crystallinity degradation of Sb2Te3 is observed after 450 °C annealing, leading to higher thermal stability than its Sb counterpart. Sb2Te3 is a promising candidate as an n‐type contact material for TMDC‐based devices such as MoS2, MoSe2, and WS2 in future VLSI electronics and various other applications.

Achieving low contact resistivity in PEDOT:PSS/n-Si solar cells

Good conductivity and transparency in the visible spectrum along with low processing temperatures and ease of fabrication make Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) a widely accepted polymer for organic-inorganic hybrid heterojunction solar cells. Although the overall conductivity of the PEDOT:PSS is high, the PSS segregates more at the surfaces of the deposited film. This leads to high contact resistivity of PEDOT:PSS film with metal and silicon. In this report, we explore the effect of the spin coating rates on the contact resistivity of PEDOT:PSS with the metal and silicon and the associated performance of PEDOT:PSS/n-Si solar cells. Two different spin speeds of 1000 rpm and 4000 rpm were used to deposit the PEDOT:PSS films over silicon. The PEDOT:PSS films were also deposited in single- and double-layer forms. We could achieve very low contact resistivity of PEDOT:PSS with silicon through spin speed optimizations. Hence, the overall performance of the PEDOT:PSS/n-Si solar cells improves with the spin speed for both single- and double-layer PEDOT:PSS film depositions.

Interface engineering to enhance charge carrier injection in Ph-BTBT-10 organic thin-film transistor with silver source-drain electrodes

We have investigated to reduce the contact resistance of organic field effect transistor (OFET) of the phenyl-benzothienobenzothiophene derivative (Ph-BTBT-10) with silver source-drain electrodes. Ph-BTBT-10 OFETs with silver electrodes show very low FET mobility and high contact resistance because the work function of silver has a large energy level misalignment with the highest occupied molecular orbital level of Ph-BTBT-10. The silver electrodes treated with self-assembled monolayers, pentafluorobenzenethiol (PFBT) and tetrafluoro-(trifluoromethyl)-benzenethiol (TTFP), show high work function and archive small contact resistance with Ph-BTBT-10. The Ph-BTBT-10 OFETs with TTFP-Ag electrodes achieved a high mobility of 1.5 cm2/Vs, and a small contact resistance of 2.1 kΩ cm.

Condition Monitoring Accuracy in Inverter-Driven Permanent Magnet Synchronous Machines Based on Motor Voltage Signature Analysis

Condition monitoring and preventative maintenance are essential for reliable and efficient operation of permanent magnet synchronous machines driven by inverters. There are two types of industrial inverter drives available: field oriented control and direct torque control. Their compensation nature and control structure are distinct and, therefore, the condition monitoring approach designed for the former control may not be applicable to the latter one. In this paper, we investigate the Motor Voltage Signature Analysis approach for both inverter drives under healthy and faulty conditions. Four typical fault conditions are addressed: turn-to-turn short circuit, high resistance contact, static eccentricity, and local demagnetization. High fidelity cosimulation is developed by coupling the finite element machine model with both control drives. The spectral elements of the commanded stator voltage are utilized as indicators for supervised classification to identify, categorize, and estimate the severity of faults. Linear discriminate analysis, k-nearest neighbor, and support vector machines are the classification techniques used. Results indicate that the condition monitoring based on the Motor Voltage Signature Analysis performs adequately in field oriented control. Nevertheless, the utilized monitoring scheme does not exhibit satisfactory performance in direct torque control owing to the nonlinear characteristics and tolerance nature of this drive.

Ultrashort channel chemical vapor deposited bilayer WS2 field-effect transistors

Two-dimensional transition metal dichalcogenides (TMDs) are potential candidates for next generation channel materials owing to their atomically thin structure and high carrier mobility, which allow for the ultimate scaling of nanoelectronics. However, TMDs-based field-effect transistors are still far from delivering the expected performance, which is mainly attributed to their high contact resistance and low saturation velocity (vsat). In this work, we report high-performance short-channel WS2 transistors based on bandgap engineering. The bilayer WS2 channel not only shows a higher average field-effect mobility (μFE) than the monolayer channel but also exhibits excellent metal-Ohmic contact using a regular physical vapor deposition deposited Ni/Au contact, reducing the Rc value to a record low value of 0.38 kΩ · μm without any intentional doping. The bilayer WS2 device of the 80 nm channel exhibits a high on-state current of 346 μA/μm at Vds = 1 V, near-zero drain-induced barrier lowering, and a record high Ion/Ioff ratio over 109. Furthermore, a record high on-state current of 635 μA/μm at Vds = 1 V and a record high vsat of 3.8 × 106 cm/s have been achieved for a shorter 18 nm channel device, much higher than previous WS2 transistors. This work reveals the intrinsically robust nature of bilayer WS2 crystals with promising potential for integration with conventional fabrication processes.

ALD-grown two-dimensional TiSx metal contacts for MoS2 field-effect transistors.

Metal contacts to MoS2 field-effect transistors (FETs) play a determinant role in the device electrical characteristics and need to be chosen carefully. Because of the Schottky barrier (SB) and the Fermi level pinning (FLP) effects that occur at the contact/MoS2 interface, MoS2 FETs often suffer from high contact resistance (Rc). One way to overcome this issue is to replace the conventional 3D bulk metal contacts with 2D counterparts. Herein, we investigate 2D metallic TiSx (x ∼ 1.8) as top contacts for MoS2 FETs. We employ atomic layer deposition (ALD) for the synthesis of both the MoS2 channels as well as the TiSx contacts and assess the electrical performance of the fabricated devices. Various thicknesses of TiSx are grown on MoS2, and the resultant devices are electrically compared to the ones with the conventional Ti metal contacts. Our findings show that the replacement of 5 nm Ti bulk contacts with only ∼1.2 nm of 2D TiSx is beneficial in improving the overall device metrics. With such ultrathin TiSx contacts, the ON-state current (ION) triples and increases to ∼35 μA μm-1. Rc also reduces by a factor of four and reaches ∼5 MΩ μm. Such performance enhancements were observed despite the SB formed at the TiSx/MoS2 interface is believed to be higher than the SB formed at the Ti/MoS2 interface. These device metric improvements could therefore be mainly associated with an increased level of electrostatic doping in MoS2, as a result of using 2D TiSx for contacting the 2D MoS2. Our findings are also well supported by TCAD device simulations.

22.8% full-area bifacial n-PERT solar cells with rear side sputtered poly-Si(n) passivating contact

High-temperature compatible passivating contacts based on phosphorus doped polysilicon (poly-Si(n)) on a thin silicon oxide, employed on the rear side of bifacial n-PERT like solar cells provide an efficiency increase while being compatible with current photovoltaic manufacturing processes, including the metallization process. However, a simple and cost-effective method for poly-Si(n) deposition is still elusive. Herein, we demonstrate DC-sputtering as a scalable and single side technique for poly-Si(n) manufacturing. First, it is demonstrated how DC-sputtered poly-Si(n) can provide high passivation (iV oc > 730 mV) and low contact resistivity (ρ c < 20 mΩ cm 2 ) when metallized by means of screen printing and firing through of Ag paste. Then, M2-sized bifacial n-PERT solar cells featuring the developed DC sputtered poly-Si(n) at the rear side and a homogenous front side B-emitter reaching a certified efficiency of 22.8% are demonstrated. Quokka simulations based on the developed DC sputtered poly-Si(n) indicate a potential up to 24.8% with an upward potential upon optimization of the front side emitter. This work highlights the feasibility of sputtered poly-Si(n) as an enabler for high-efficiency n-type solar cells. • Ex-situ P-doped PVD sputtered poly-Si passivating contacts integrated in M2 sized bifacial n-PERT solar cells. • M2 bifacial n-PERT devices with 22.8% certified efficiency demonstrated. • Integration of 100 nm of ex-situ doped sputtered poly-Si with screen printing and firing through of Ag paste. • Roadmap toward 25% efficiency presented.