Miniatyriserade punktkontakter för tunnfilmssolceller
Tidsperiod: 2012-01-01 till 2014-12-31
Projektledare: Marika Edoff
Budget: 3 000 000 SEK
The aim of the work is to increase the efficiency of high quality thin film solar cells by reducing the recombination process at the back contact. The project will also assess fundamental properties of the Cu(In,Ga)Se2 material, e.g. influence of grain boundaries on lateral transport mechanisms in addition to the back contact properties. We will reduce the back contact area from 100% to 5% or less using a combination of a passivation layer with small point contacts by: 1) Contacting in nano-holes, either by a lift-off process using dispersed nano-particles which are removed after deposition of passivation layer, or by photo-lithography. 2) Contacting by means of nanoparticles deposited before the passivation layer. Cu(In,Ga)Se2 thin film solar cells with up to 20.3 % efficiency have been reported, with best results in the group at above 18 %. At this level, minority carrier diffusion lengths of above 1 µm are estimated. This material is suited for the project, which will include: -Two-dimensional modelling for size and spacing. - Nano-particle fabrication, both for lift-off and for contacting. Nano-particles with 200 nm in diameter and with a spacing of 2-5 µm is the starting point for proof-of-concept. - The passivation layer. Two alternatives will be tested in the first round of experiments: ZnS and MgO. -Characterization of materials and devices. The characterization will be by electron microscopy based methods and by standard and advanced electrical characterization.