Dear Olasunkanmi Razaq Kesinro ,

Most of technical improvements on solar cells are based on experimental works. Although some researchers do that, post-annealing after fabrication of a solar cell device is not common. A solar cell is consisted of layers and each layer has its own properties. The most important role of annealing is maybe its effect on crystallinity leading to effects on electrical, optical and structural properties. When you impose a temperature or a way of post-annealing on whole device, you impose it in fact on every layer uniformly. However, every layer has its own properties and this may have advantages for one layer and disadvantages for another, simultaneously. I think optimization of layers, step by step, could be more suite rather than optimization of whole device entirely.

On the other hand, I think annealing a device can cause the metal electrode diffusion into the active layerwhich can result in resistance, so I think annealing after setting metal contact might not be a good advise.

Nevertheless, there are some articles (linked at below) about annealing of whole device with positive and negative results; however, experimental works on solar cells are hardly affected by fabrication process. You may fabricate a solar cell without efficiency and other one make it just like you, but in another lab, with an efficiency.

Fabrication, characterization and annealing of polymer-fullerene bulk heterojunction organic solar cells, AIP Conference Proceedings 1837, 040071 (2017); doi: 10.1063/1.4982155

Effect of Annealing Treatment on the Performance of Organic Solar Cell, Tengku Hasnan Tengku Aziz et al. ICSE2010 Proc. 2010, Melaka, Malaysia.

Thank you, Milad Fallah. Your response is very insightful.

Dear Olasunkammi,

Welcom! Hope you are well and your experiment is successful.

Milad explained some annealling effects on the properties of solar cells.

Really post heat treatment or annealing at this relatively low temperature may have little effect on the recrystallization of the different layers especially the semicondcutor layers. Its effect is to produce a better contact between the metal and the contacting semicondcutor as this interface must be ohmic with low resistance. The experience shows it is required to anneal the metal after the deposition to affect good contact. The issue is that the suitable annealing temperature is to be found in an experimental basis.

If you do not have pv effect means that you you have most probably a short circuit. This short is because of the existence of pinholes. Then when you deposit aluminum it covers the pin holes and the upper metal and the lower metals meet each other causing short.

You can see the pinholes by the microscope.

You have to reduce them and divide your cell into smaller cells such that you can find solar cells with no pinholes that give pv performance.

Best wishes