/Next-generation high-efficiency triple junction solar cells based on perovskites and silicon

Next-generation high-efficiency triple junction solar cells based on perovskites and silicon

PhD - Genk | More than two weeks ago

Taking the first steps towards the next-to-next-generation PV cell technology node (n+2).

Harnessing solar energy ever more efficiently yet cost-effectively has been an age-old pursuit for terrestrial photovoltaics (PV). Silicon (Si), being an abundant material and a stable absorber, has dominated the PV market since the beginning with successive generations of cell technology raising the efficiency bar higher and higher. With single junction Si almost at its limits (practical limit of ~28% and theoretical Auger limit of 29.4%), the PV community has been focusing its R&D efforts increasingly on dual junction solar cells, where two absorbers act in a complementary way to raise the headroom for the efficiency of the eventual tandem device. The most popular tandem combination is using the well-known Si as the bottom absorber together with the promising low-cost, but highly-efficient thin film perovskite (Pk) top absorber. Pk/Si tandems have attained 31.25%, 29.0% and 30.1% in 2-terminal, 3-terminal and 4-terminal configurations, achieved by EPFL/CSEM, CSEM and Solliance, respectively, all in 2022. Higher efficiencies with long lifetime at limited additional costs would continue to drive down costs per Wp and kWh at system level. Multi-pronged challenges in terms of their intrinsic and operational stability, the choice of processing methods and materials, upscaling to large-dimensions, and integration with module materials, are being widely investigated for Pk/Si tandems.

 

In this PhD topic, we want to take the first steps towards the next-to-next-generation PV technology, i.e., triple junction solar cells, building further on the Pk/Si tandem research, by adding an additional Pk cell on top, which allows for device efficiencies >35%. The device architecture will be 2-terminal with three absorbers connected monolithically (and electrically) in series. The first challenge is the engineering of the bandgap of the Pk absorbers to achieve ~1.5-1.6 eV and ~1.8-1.9 eV for the middle and top cells, respectively. While high-efficient and stable Pk compositions have been widely reported in the 1.5-1.6 eV range, wide bandgap (1.8-1.9 eV) Pk absorbers are prone to degradation due to halide segregation, which must be solved. The second challenge is the processing of the top Pk absorber on top of the middle Pk absorber without damaging the latter. Compact interlayers between the Pk sub-cells, processed using suitable damage-free methods and materials, need to be developed. The third challenge is the opto-electrical optimization of a quite complex multi-material stack such that optical and electrical loss pathways are minimized towards achieving high efficiencies. The final challenge is to opt for materials that are abundant, i.e., avoiding or drastically reducing scarce indium, silver and bismuth in the device stack.

 

The successful execution of this work requires intense step-wise experimentation, supported by opto-electrical characterization and modeling. Perseverance, creativity and collaboration will stand you in good stead in working closely with the experts within the team, and across and beyond the organization. The PhD topic will contribute to and benefit from a recently-started European project, called TRIUMPH, funded by the European Commission under grant agreement no.: 101075725.
 

Next-generation high-efficiency triple junction solar cells based on perovskites and silicon


Required background: M.Sc. in Physics, Chemistry, Materials or Electrical Engineering. Curious, autonomous, lab-oriented and a team player.

Type of work: 80% experimentation and characterization, 10% modeling, 10% literature

Supervisor: Bart Vermang

Co-supervisor: Jef Poortmans

Daily advisor: Hariharsudan Sivaramakrishnan Radhakrishnan, Yinghuan Kuang

The reference code for this position is 2023-103. Mention this reference code on your application form.

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