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In this paper, the impact of the N 2 anneal on laser processed silicon was investigated using photoluminescence (PL) imaging through comparing the PL signal of laser processed samples before and after N 2 anneal. The samples capped with different dielectrics or without any dielectric (bare surface) prior to the laser processing were used, enabling the evaluation of the influence of the N 2 anneal on the defects caused both by laser thermal effect and by the existence of dielectrics. Generally, it was found that N 2 anneal is an effective way to reduce both the laser and dielectric induced defects. [ABSTRACT FROM AUTHOR]

Laser doping of crystalline silicon has been the subject of intense research over the past decade, due to its potential to enable the fabrication of high efficiency and low-cost crystalline silicon solar cells. Information regarding the doping profile created by the process is critical for process optimisation, however is generally difficult to obtain. In this paper, a relatively new technique for characterising laser doping cross-sections — Secondary Electron Microscopy Dopant Contrast Image (SEMDCI) — is compared with the widely used Electron Beam Induced Current (EBIC) method. A good agreement between the two techniques regarding the p-n junction profile is demonstrated. The differences between the methods are attributed to the difference of the sensitivity. The comparison demonstrates the reliability and usefulness of the SEMDCI as a characterisation method for laser doping, which shows both the p-n junction outline and dopant distribution within the doped regions. The differences between the methods and the challenges associated with the application of the SEMDCI method are also discussed. [ABSTRACT FROM AUTHOR]

Ion implantation and laser processing technologies are very attractive for the fabrication of industrially feasible interdigitated back-contact (IBC) solar cells. In this work, p + emitters were fabricated by boron implantation and laser annealing, and the electrical properties of emitters were investigated. An emitter sheet resistance ( R sh ) in the range of 30-200 Ω/□ could be achieved by varying the implanted dose. The saturation current density ( J oe ) of the passivated p + emitter with R sh of ∼125 Ω/□ reached 95 fA/cm 2 , and the contact resistivity was determined to be as low as 5×10 -6 Ω·cm 2 . Such localized p + emitters can be applied to n-type IBC solar cells, which could avoid the high temperature thermal annealing step and related problems. [ABSTRACT FROM AUTHOR]

We report a novel flexible solar tracking system based on a photothermal-thermomechanical (PT-TM) actuator comprised of Ti 3 C 2 T x MXene and polyvinylidene fluoride (PVDF) bilayer. The actuation function of the proposed device originates from photothermal and surface plasmon-assisted effects in MXenes, coupled with thermomechanical deformation of in-plane aligned PVDF polymer. Two types of solar tracking modes are evaluated based on the experimental deformation behavior of the PT-TM actuator. We find that the uniaxial East-West solar tracking option increases the overall energy intensity reaching the solar module by over 30%, in comparison with the optimized tilting-controlled mode. We also demonstrate the thermally driven self-oscillation of the MXene-PVDF device, which may have promising potential for optically and thermally driven soft robotics. The PT-TM actuator devices display robust mechanical strength and durability, with no noticeable degradation in their performance after more than 1000 cycles. A novel flexible photothermal-thermomechanical (PT-TM) actuator comprised of Ti 3 C 2 T x MXene and polyvinylidene fluoride (PVDF) bilayer is developed. The actuation function of the proposed device originates from photothermal and surface plasmon-assisted absorption in MXenes, coupled with thermomechanical deformation of in-plane aligned PVDF polymer. The actuator can greatly enhance solar energy harvesting compared to a tilt-controlled solar tracking system. Image 1 • The actuation mechanism is shown to originate from thermomechanical deformation of the in-plane aligned PVDF polymer chains coupled with optical absorption effects in MXene. • We demonstrate that our autonomous actuator can be used in a solar tracking application and can increase the overall energy intensity reaching the solar module by over 30% compared to the optimized tilting-controlled mode. • We also demonstrate thermally driven self-oscillation of MXene-PVDF device, which may have potential in optically and thermally driven soft robotics. [ABSTRACT FROM AUTHOR]

In this work, tunnel SiO 2 /a-Si:H stacks are trialed as passivated contacts to laser doped p + and n + regions. The passivation performance and contact resistivity are investigated as a function of the tunnel SiO 2 thickness and annealing condition. We find that the SiO 2 /a-Si:H stack provides excellent passivation to laser doped n + regions, with corresponding low recombination current density ( J o ) values. A lower level of surface passivation is achieved by the SiO 2 /a-Si:H stack on laser doped p + regions. A post-deposition forming gas anneal (FGA) at 400 °C is found to improve the passivation performance to laser doped p + regions and deteriorate the passivation to laser doped n + regions. Acceptable contact resistivity ( ρ c ) values have been obtained for both laser doped n + and p + regions after aluminum metallization and a post FGA to activate the alloying process between the a-Si:H and aluminum layer. In the final part of this work implementation of the passivated contacts to laser doped regions into a simplified interdigitated back-contact (IBC) solar cell fabrication process is proposed. Simulation result suggests that IBC device with an efficiency of up to 23% can be achieved using the obtained experimental results. [ABSTRACT FROM AUTHOR]

This paper outlines the development of fully screen-printed, uniformly diffused, bifacial, n -type silicon solar cells produced using a lean processing sequence and industry-standard equipment. An average batch efficiency of 21.4% was measured at standard test conditions for an optimised bifacial cell batch (i.e. illumination on the front surface only). The results of open circuit voltage ( V OC ) and fill factor ( FF ) loss analyses are presented for select batches. By targeting reductions in the largest recombination components, optimised batch V OC was increased by 15 mV compared to the baseline case. The two largest recombination components limiting V OC in optimised devices are front contact recombination and passivated rear surface recombination. The largest FF loss components for optimised devices are the emitter sheet resistance and front contact resistance. [ABSTRACT FROM AUTHOR]