Novel intermediate-band solar cells from nanowires
- Reference number
- UKR22-0029
- Project leader
- Rudko, Galyna
- Start and end dates
- 220501-231231
- Amount granted
- 2 000 000 SEK
- Administrative organization
- Linköping University
- Research area
- Materials Science and Technology
Summary
Utilization of semiconductor nanowires (NWs) in light emitting devices and solar cells promises to improve device efficiency while decreasing material consumption and costs. This project suggests utilizing novel highly-mismatched III-V alloys in the NW architecture for further boosting device performance. Our specific aims are: 1) "to understand key material-related parameters of novel nanowires (NWs) from highly mismatched semiconductors (such as dilute nitrides), and their dependence on structural design; 2) "to gain general knowledge on unknown fundamental properties of different crystal polytypes of such NWs, to exploit band structure engineering, and to explore spin-enabling new functionality for potential applications in photovoltaics; 3) "to single out optimum structural design of prototype NW solar cells for efficient energy harvesting utilizing an intermediate-band approach. To realize our research objectives, the project is divided into three interconnected work packages (WP): (i) solving material-related issues; (ii) understanding fundamental electronic properties; and (iii) developing the optimum design. The planned research activities include modeling and comprehensive structural, optical, spin resonance and electrical characterization studies, which will be conducted for optimization of growth conditions and structural design.
Popular science description
With increasing environment concern and rapidly decreasing amount of other conventional energy resources, harvesting energy from sunlight using photovoltaic technology and saving energy by maximizing device efficiency are currently being recognized as essential components of future global energy management. In the case of photovoltaics, nanowire (NW) architecture of solar cells provides potential advantages over the planar design as it allows one (i) to reduce material consumption; (ii) to improve absorption of solar energy due to light trapping within NWs arrays; (iii) to tune material properties using band structure engineering; and (iv) to increase defect tolerance due to efficient strain relaxation in NWs. The solar cell efficiency can be further improved using the so-called intermediate band (IB) approach, i.e. utilizing an IB material sandwiched between two ordinary n- and p-type semiconductors, which act as selective contacts to the conduction band (CB) and valence band (VB), respectively. In an IB material, sub-bandgap energy photons are absorbed through transitions from the VB to the IB and from the IB to the CB, which together add up to the current of conventional photons absorbed through the VB–CB transition. The promising materials that can act as IB are novel dilute nitride alloys made of highly mismatched III-V semiconductors. These materials are derived from conventional III-V semiconductors such as (Ga,In)(P,As) by the insertion of N atoms into the group V sublattice. These materials exhibit unusual energy band structure with a narrow band of states located in the band gap of the host material suitable as IB. In this program we suggest to combine advantages of novel nanostructure architecture with those offered by dilute nitride alloys, for the next generation of solar cells with record efficiencies. The specific aims of the program are: 1) "to understand key material-related parameters of novel NWs from dilute nitrides, and their dependence on structural design; 2) "to gain general knowledge on unknown fundamental properties of different crystal polytypes of such NWs, to exploit band structure engineering, and to explore spin-enabling new functionality for potential applications in photovoltaics; 3) "to single out optimum structural design of prototype NW solar cells for efficient energy harvesting utilizing an intermediate-band approach with a high efficiency.