Speaker
Description
As global energy demand rises and the transition towards carbon-neutral energy systems accelerates, developing highly efficient energy-harvesting and electronic devices is becoming increasingly important. Diamond is an exceptional platform for nanoengineered optoelectronics owing to its ultra-wide band gap, outstanding carrier mobility, and high thermal conductivity. Crucially, its wide band gap enables unique defect-engineering strategies that are difficult to realise in conventional semiconductors.
With this aim, we present a unified first-principles framework that combines density functional theory with GW corrections, Bethe-Salpeter equation calculations, and carrier transport modelling coupled to a device-level Poisson solver to investigate two novel device architectures. The first is an intermediate-band photovoltaic device based on boron-vacancy-boron (BVB) cluster defects. The BVB defect introduces multiple intermediate bands within the diamond band gap, enabling the absorption of sub-bandgap photons and providing a promising route towards overcoming the Shockley-Queisser efficiency limit of conventional solar cells. The second architecture is a phosphorus-based PN junction in which both regions are doped with the same dopant species. In this design, the p-type region is formed through phosphorus-vacancy (PV) complexes, enabling a simplified single-dopant device concept that could reduce manufacturing complexity, minimise cross-contamination and streamline fabrication processes.
Our results show that BVB defects provide strong intermediate-band optical functionality while preserving the favourable transport and thermal properties of diamond. We further establish practical design guidelines for photovoltaic operation, including optimal crystal orientation, absorber thickness and junction doping profiles. For the phosphorus-based diode, we demonstrate that PV defects support impurity-band transport and high conductivity, making them suitable for degenerate p-type applications such as tunnel diodes and asymmetric junctions. Furthermore, its temperature-dependent Seebeck coefficient anisotropy and sign-reversal offer novel thermal management pathways.
The outcomes of this investigation constitute key technological guidelines that can be promptly applied to the design and fabrication of next-generation, high-performance diamond optoelectronic devices.
This work was supported by the project “The Energy Conversion and Storage”, funded as project No. CZ.02.01.01/00/22_008/0004617 by Programme Johannes Amos Commenius, call Excellent Research. This work was supported by the Ministry of Education, Youth and Sports of the Czech Republic through the e-INFRA CZ (ID:90254). The access to the computational infrastructure of the OP VVV funded project CZ.02.1.01/0.0/0.0/16_019/0000765 “Research Center for Informatics” is also gratefully acknowledged.