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35th European Photovoltaic Solar Energy Conference and Exhibition; 456-459, Sputtered indium tin oxide (ITO) is a widespread used material for application as transparent conducting oxide as the front contact of rear-junction silicon heterojunction solar cells. Standard ITO films suffer from too high parasitic absorption in both the short- and the long-wavelength range. The aim of this contribution is to investigate lower absorbing TCOs deposited with industrial DC sputtering from rotatable targets. High Voc values >735 mV demonstrate that in spite of the high-power industrial DC sputter process no significant sputter damage is observed, independent of the target material. Cell efficiencies up to 23.3% are obtained with titanium-doped (ITiO) and tin-doped indium oxide (ITO 99/1). The highest short circuit current values of 39.6 mA/cm2 are reached with an ultimately low-carrier and high-mobility indium-oxide-based material. The cell efficiency in this case, however, is over-compensated by a too low FF, mostly due to a higher contact resistivity and TCO sheet resistances. We ascribe this effect to the very low carrier concentration.

33rd European Photovoltaic Solar Energy Conference and Exhibition; 358-361, Interdigitated back contact (IBC) solar cells offer one of the most promising routes towards highest device efficiencies and have a high potential for low cost production sequences. In this work, we replace typical patterning steps and high-temperature diffusions in IBC device fabrication by means of laser processing. We report on the fabrication of a 22.8% efficient all-laser-doped IBC solar cell with localized boron and phosphorus doped contacts. By means of three-dimensional numerical device modelling we demonstrate that this cell is limited by recombination at the localized n+ contacts and determine an efficiency potential of 24.5% with improved laser parameters and surface passivation.

29th European Photovoltaic Solar Energy Conference and Exhibition; 666-671, The interdigitated back contact (IBC) solar cells developed at ANU have resulted in an independently confirmed designated-area efficiency of 24.4 ± 0.7%, featuring short-circuit current density of 41.95 mA/cm2, opencircuit voltage of 703 mV and 82.7% fill-factor. The cell, 2 x 2 cm2 in area, was fabricated on a 230 μm thick 1.5 Ω.cm n-type Cz wafer, utilising PECVD SiNx front surface passivation without front surface diffusion, rear side thermal oxide / LPCVD Si3N4 passivation stack and evaporated aluminium contacts with a finger-to-finger pitch of 500 μm. This paper describes the design and fabrication of lab-scale high-efficiency IBC cells. Characterisation of optical and electronic properties of the best produced cell is made, with subsequent incorporation into 3D device modelling used to accurately quantify all losses. Loss analysis demonstrates that bulk and emitter recombination, bulk resistive and optical losses are dominant, and suggests a clear route to efficiencies in excess of 25%. Additionally, laser processing is explored as a means to simplify the manufacture of IBC cells, with a confirmed efficiency of 23.5% recorded for cells fabricated using damage-free deep UV laser ablation for contact formation. Meanwhile alllaser doped cells, where every doping and patterning step is performed by lasers, are demonstrated with a preliminary result of 19.1% conversion efficiency recorded.

28th European Photovoltaic Solar Energy Conference and Exhibition; 2678-2683, Plasmonic effects on metal particles are a promising way of trapping light in solar cells. We experimentally demonstrate enhanced absorptance in thin silicon using metal nanoparticle arrays in conjunction with a rear mirror. The nanoimprint process is a fast and scaleable method for producing nanoscale light trapping structures. Incorporating both nanoparticle arrays and a rear mirror leads to a substantial increase in absorptance, due to resonant interference effects. We numerically simulate a planar Ag mirror deposited onto a planarized sol-gel silicon dioxide (SiO2) layer, and show the enhancement could reach 53%. We also find that a conformal Ag mirror deposited on a sputtered SiO2 layer could give similar enhancement. Experimentally, we derive predicted Jsc enhancements of up to 2.8 mA/cm2 from absorptance measurements. The experimental results show good qualitative agreement with numerical simulations as the thickness is increased, with clear evidence of absorptance enhancement via a Fabry-Perot resonance effect.

28th European Photovoltaic Solar Energy Conference and Exhibition; 1057-1060, Laser chemical processing (LCP) has been proven to be an effective technology to form selective emitters and local back surface fields for high efficiency silicon solar cells. In this work, LCP n-type doping formed through different dielectric layers is presented, and is characterisaed by changes in the effective lifetime (eff) and emitter saturation current density (Joe). With the same LCP parameters, the sheet resistance of the n-type doping area could be made as low as 15-20 Ω/ under various passivation layers. As the doping area fraction increases, we observe clear degradation in eff and Joe with different passivation layers. Under the same LCP parameters and doping fraction, SiO2 passivated samples show a reduced eff and Joe degradation than those pssivated by SiNx. The reason could be attributed to the different thermal properties of SiO2 and SiNx dielectric layers and the passivation effects of the H3PO4 doping solution on the Si-SiO2 interface.