Research Activities

Research interest I: Scanning Probe Microscopy Characterisations

The characterization of materials plays a crucial role in the field of photovoltaic (PV) research, enabling a comprehensive understanding of the various factors that influence performance. It is essential to establish a clear connection between the properties of the underlying materials and the performance of the devices. To achieve this, several non-destructive techniques provide spatially resolved characterization, offering insights into the charge carrier properties of local structures and defects. Luminescence techniques leverage a radiative phenomenon that involves the emission of photons from semiconductors. These techniques have gained wide popularity for rapid imaging of large silicon wafers. They offer spatial resolutions ranging from 100nm (u-PL) to a few nanometers, enabling detailed analysis at the microscopic level. By contrast, scanning probe microscopy (SPM) techniques employ sharp tips that scan extremely close to or make contact with the semiconductor surface. This approach provides spatial resolutions ranging from 0.1nm (STM) to several nanometers (KPFM and C-AFM). In addition to imaging capabilities, SPM techniques allow the exploration of morphology-dependent functional properties, including piezoelectric properties, thermal properties, magnetic properties, mechanical properties, and more.

*See our publications:

Research interest II: Indoor Photovoltaics

The significant increase in demand for low-power devices for “Internet of Things” (IoT) applications has caught our attention. Indoor PV technologies suitable to power these applications are underdeveloped, having a maximum efficiency at 30-35% though the theoretical efficiency limit is 52% under 1 W/m2 indoor lightings. The main problem is the lack of outstanding PV devices with optimal band gaps (1.8-2.0eV) for the low light intensity indoor spectrum. Mainstream inorganic solar cell materials such as silicon and GaAs perform un-optimally in these conditions. Our group aim to develop highly efficient (35-40%) PV technology by utilising wide bandgap halide perovskites to integrate to and power indoor IoT devices.

*See our publications:

Research Interest III: Space Solar Cell

While utilisation of the sunlight for generating electricity sounds like a perfect idea, the amount of solar energy we can use varies according to the time of day and the season of the year as well as geographical location. For instance, the UK gets only ~60% of the solar radiation found in the Equator and the average annual number of daily sun hours is only around 4 hours/day. Space Based Solar Power (SBSP) is a concept of collecting energy in outer space using space photovoltaics cells and transmitting it to Earth. The advantage of collecting solar energy in space is a higher collection of energy due to the lack of reflection and absorption by the atmosphere, the possibility of no (or very little) night, and better ability to orient to face the sun. Various SBSP proposals have been researched since the early 1970s, but none are economically viable with present-day space launch infrastructure. The main cost of SBSP is the launch costs of satellites. During 1980, payload delivered to low Earth orbit was $85,216/kg which has significantly dropped to $957/kg (Falcon Heavy) and NASA aims to reduce the cost to tens of dollars per kg by 2040. In contrast, the cost of space PV that consists of GaAs based multijunction solar cells remained almost the same due to the high cost of GaAs wafers. Unfortunately, silicon solar cells cannot be used in space due to their low radiation tolerance, therefore, searching for alternate cheap solar cells for space applications is a priority that makes SBSP technology feasible. Recently, halide perovskites (HPs) have been recently emerged for various optoelectronic applications due to their exceptional optoelectronic properties as well as their cheap material cost. Also, some paramilitary studies have shown the great potential of HPs for space applications due to their high energy radiation tolerance. To fully corroborate their facilities for space applications, HPs need to be tested under a lot more diverse conditions such as high vacuum with continuous illumination conditions.

*See our publications:

https://iopscience.iop.org/article/10.1088/2515-7655/ad7404/meta