Effect of solvent additives on bulk heterojunction morphology of organic photovoltaics and their impact on device performance

Polymeric Materials for Conversion of Electromagnetic Waves from the Sun to Electric Power

Solar photoelectric energy converted into electricity requires large surface areas with incident light and flexible materials to capture these light emissions. Currently, sunlight rays are converted to electrical energy using silicon polymeric material with efficiency up to 22%. The majority of the energy is lost during conversion due to an energy gap between sunlight photons and polymer energy transformation. This energy conversion also depends on the morphology of present polymeric materials. Therefore, it is very important to construct mechanisms of highest energy occupied molecular orbitals (HOMO)s and the lowest energy unoccupied molecular orbitals (LUMO)s to increase the efficiency of conversion. The organic and inorganic solar cells used as dyes can absorb more photons from sunlight and the energy gap will be less for better conversion of energy to electricity than the conventional solar cells. This paper provides an up-to-date review on the performance, characterization, and reliability of different composite polymeric materials for energy conversion. Specific attention has been given to organic solar cells because of their several advantages over others, such as their low-energy payback time, conversion efficiency and greenhouse emissions. Finally, this paper provides the recent progress on the application of both organic and inorganic solar cells for electric power generations together with several challenges that are currently faced.

The importance of solvent quality on the modification of conjugated polymer conformation and thermodynamics with illumination

Device efficiency in key organic electronic devices such as organic photovoltaics, field transistors, and light emitting diodes has long been known to be closely tied to the conformation of the conjugated polymer chains which make up the active layers. Our previous results show that light exposure can have a profound effect on the structure and assembly of these optoelectronic materials in solution. In order to advance our understanding of the role which solvent quality plays in this phenomenon, we have further studied the modulation of these illumination dependent structural changes on the key benchmark conjugated polymers P3HT and MEH-PPV as a function of solvent quality over a wide range of polymer solubilities. Analysis of this data indicates that use of poorer conjugated polymer solvents ultimately results in larger absolute alterations to polymer conformation, denoting the crucial role which solution thermodynamics plays in this generic effect. This discovery opens the door to controlling final device morphology through careful manipulation of solvent composition during solution based device casting techniques, moving our efforts closer to the development of a powerful, non-destructive, and tunable method for light-driven control of polymer conformation in novel light-responsive organic materials.

Organic and perovskite solar cells: Working principles, materials and interfaces

In the last decades organic solar cells (OSCs) have been considered as a promising photovoltaic technology with the potential to provide reasonable power conversion efficiencies combined with low cost and easy processability. Unexpectedly, Perovskite Solar Cells (PSCs) have experienced unprecedented rise in Power Conversion Efficiency (PCE) thus emerging as a highly efficient photovoltaic technology. OSCs and PSCs are two different kind of devices with distinct charge generation mechanism, which however share some similarities in the materials processing, thus standard strategies developed for OSCs are currently being employed in PSCs. In this article, we recapitulate the main processes in these two types of photovoltaic technologies with an emphasis on interfacial processes and interfacial modification, spotlighting the materials and newest approaches in the interfacial engineering. We discuss on the relevance of well-known materials coming from the OSCs field, which are now being tested in the PSCs field, while maintaining a focus on the importance of the material design for highly efficient, stable and accessible solar cells.