CORDIS - EU research results

Novel MESO-SUPERstructured solar CELLS with enhanced performance and stability

Final Report Summary - MESO-SUPERCELLS (Novel MESO-SUPERstructured solar CELLS with enhanced performance and stability)

Renewables are considered to be the main energy source to reduce pollution and mitigate climate change. Because of its unmatched resource potential, solar energy photovoltaic (PV) utilization has been the subject of intense research, development and deployment efforts. PV industry is the largest optoelectronics sector in the world, bigger than flat-panel displays or solid-state lighting. Commercially available Si panels currently account for 90% of total solar panel production, rendering people arguing that silicon has already shown to be the winner and further R&D should focus primarily on advanced silicon concepts.

However, PV researchers note that the solar energy conversion efficiency of commercial PV modules is still less than half of the theoretical limit and, since silicon is already commercialized, further public investment should focus on alternatives such as thin films. Undoubtedly, the most promising representative of thin films is the perovskite solar cell, the field of which has experienced a revolution during the last years. The photovoltaic community has never before witnessed such a rapidly advancing technology with genuine promise for commercialization; in 2012, the efficiencies were lying at 9-11% while now exert 22%.

The proposal “MESO-SUPERCELLS” dealt exactly with the investigation of the perovskite solar cell with the overall objective being the predictable jump in power output. The overall goal of the project was further analysed in 3 (more specific) key science and technical objectives:

Objective 1: Optimizing perovskite crystallization and interfaces to enhance photovoltaic efficiencies of solid-stated solar cells.

Work towards objective: We were able to identify a specific crystallization enhancement additive for the CH3NH3PbI3 perovskite, which improved the quality of the semiconductor, leading to enhanced solar cell device performance and improved reproducibility. Our work highlights that much further scope remains to achieve entirely electronically homogeneous polycrystalline thin films. Understanding the subtleties of crystallization from the composition of the solutions to the final crystallized films is still in its infancy, and we expect that the discovery of other ‘impurity’ additives to be important for the ongoing advancement of the perovskite technology.

Objective 2: Deep understanding of the fundamental processes and mechanisms behind the operation of this novel type of solar cell.

Towards objective 2: We have tried to understand the fundamental processes and mechanisms behind the operation of the perovskite solar cells. Different systems were thoroughly studied concluding that a) the doping level of the p-type material should be controlled in order to attain high stabilized output power, b) the mesostructured layer is playing a specific electronic role (probably enhancing the doping of the perovskite) except of its function to enhance surface coverage and c) the crystallization kinetics affect the recombination dynamics of flat heterojunction solar cells d) recombination can be severely suppressed upon use of a fast-crystallization agent, even though the grain size is generally small.

Objective 3: Preparation of environmentally friendly perovskite solar cells

Towards objective 3: We worked extensively on lead-free (Sn2+ and Ge2+) perovskites to fight against the toxicity of lead and used environmentally friendly solvents to replace harmful and toxic solvents (such as DMF), frequently used to dissolve perovskite components. Especially the results on the use of environmentally friendly solvents during perovskite solar cells preparation are really important. The approach has imminent scope to propose the use of relatively harmless solvents which, otherwise, can be really difficult to handle/recover or eliminate in scaled perovskite photovoltaic processing, raising health and safety issues and increasing the production cost.

Socio-economic impact and societal implications: The research results could (i) lead closer towards the commercialization of this new technology, (ii) contribute to the Europe’s continuing research for “clean and efficient energy”, creating reliable “low carbon” solar electricity, (iii) promote the Excellence of the European Research Area, by building the strongest Photovoltaic research community in the field of 3rd generation solar cells, iv) fight against “energy poverty”, a major problem lately met in European countries dealing with serious financial issues and v) make a step forward towards economic prosperity of the entire world.

Target groups: especially our results on the use of environmentally friendly solvents during the solar cell preparation could receive attention from PV industry and venture investors. In a more general wording, good results on every aspect of solar energy systems could receive support from technologists, regulators, politicians and environmental groups.

Scientist in charge:
Prof Henry J. Snaith, FRS,
Clarendon Laboratory,
Parks Road,
Tel: +44 (0)1865 272380

Marie-Curie Fellow:
Dr. Thomas Stergiopoulos
Lecturer in Physical Chemistry/Electrochemistry
Aristotle University of Thessaloniki (Greece)
Department of Chemistry
54124 Thessaloniki
tel: 00302310997752