This laboratory experiment is designed to train undergraduate students in the fundamental steps followed in engineering solution-processed organic solar cells and to offer insight on the operating principles of said device. Bulk heterojunction (BHJ) organic solar cells represent a photovoltaic architecture which has attracted a lot of attention due to its promising properties; moreover, this architecture, due to its low cost and potential, is continuously being investigated and improved. This paper is intended as a useful step-by-step guide for students and researchers to learn how to construct such a device. Another primary objective of this article is to highlight the importance of optimizing device performance through enhancing the optical, electrical, and morphological properties of the materials selected as building blocks. Once a completed organic solar cell is made, students will also learn how to investigate and assess its performance through a series of spectroscopic, electrical, and morphological characterization measurements.

A novel solution-processed, graphene-based material was synthesized by treating graphene oxide (GO) with 2,5,7-trinitro-9-oxo-fluorenone-4-carboxylic acid (TNF-COOH) moieties, via simple synthetic routes. The yielded molecule N-[(carbamoyl-GO)ethyl]-N′-[(carbamoyl)-(2,5,7-trinitro-9-oxo-fluorene)] (GO-TNF) was thoroughly characterized and it was shown that it presents favorable highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels to function as a bridge component between the polymeric donor poly({4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl}{3-fluoro-2-[(2-ethylhexyl)carbonyl] thieno[3,4-b]thiophenediyl}) (PTB7) and the fullerene derivative acceptor [6,6]-phenyl-C₇₁-butyric-acid-methylester (PC₇₁BM). In this context, a GO-TNF based ink was prepared and directly incorporated within the binary photoactive layer, in different volume ratios (1%–3% ratio to the blend) for the effective realization of inverted ternary organic solar cells (OSCs) of the structure ITO/PFN/PTB7:GO-TNF:PC₇₁BM/MoO₃/Al. The addition of 2% v/v GO-TNF ink led to a champion power conversion efficiency (PCE) of 8.71% that was enhanced by ~13% as compared to the reference cell.

Although graphene's superior electrical, optoelectronic, thermal, and mechanical properties have been evident for 20 years now, its poor water dispersibility has hindered its incorporation in many types of applications and technologies. Strong examples of this are biomedical and environmental applications and devices that require non‐toxic, biocompatible media and not toxic organic solvents like N‐N’‐Dimethylformamide, in which graphene is readily dispersible. In this work, we investigate a new way to prepare high‐concentration and stable graphene dispersions in water by employing porphyrin‐based compounds as stabilisers. To this end, electrochemically exfoliated graphene (EEG) and assess the potential of five porphyrins and metalloporphyrins are prepared to disperse EEG in water successfully. The dispersibility and stability of EEG in each porphyrin aqueous solution are evaluated by recording their UV–vis absorption spectra. Two of the synthesised compounds, namely sodium salt of 5,10,15,20‐tetrakis(4‐carboxyphenyl)‐porphyrin or TCPP and sodium salt of [5,10,15,20‐tetrakis(4‐carboxyphenyl)‐porphyrinato]tin(IV) or Sn‐TCPP , are successful in stably dispersing EEG in water. The intermolecular interaction between the EEG flakes and [H ₂ TCPP]Na ₄ and [Sn(OH) ₂ TCPP]Na ₄ molecules are investigated via fluorescence emission spectroscopy. Finally, solid thin films of the EEG(TCPP) and EEG(Sn‐TCPP) dispersions are prepared via spray‐coating, and their optoelectronic properties and surface morphology are investigated.