**6. References**

24 Solar Cells – New Aspects and Solutions

The device performance depends greatly on annealing temperatures as clearly seen from Fig. 19. The reasons for the performance to be improved by the annealing process have been widely investigated and discussed in section 3. It is clear that for an efficient bulk HJ polymer solar cell, *D* and *A* domains must be small enough so that most of the excitons can diffuse into the *D/A* interfaces before they decay. At the same time, the interpenetrating transport network must be formed for the efficient charge transport. Thus, the morphology optimization is of great important. By varying the annealing condition, the morphology can

Fig. 19. (a) and (b): Relations of device performance and annealing conditions. The

optimized performance when it has been annealed at 160oC for 10 min.

These results were related to the better morphology as discussed in previous and also related to the increase of the charge carrier mobility. The same reason should also be responsible for our results. The highest *PCE* in our experiments is achieved when the annealing temperature is 160oC which is very close to the annealing temperatures reported by Ma (Ma et al., 2005). The analysis of changes in film morphology has shown that the changes in film crystallinity and aggregation within the film PCBM nanophase lead to the improved solar characteristics at this temperature. When the annealing temperature is increased, a steady enhancement of *VOC* is observed because the e-beam evaporated Al can induce dipoles at the interface between active layer and cathode [Zhang et al., 2009]. As shown in Fig. 19, the device shows the

In polymer solar cells, because of the optical interference effect, the total exciton generation rate does not increase monotonically with the increase of the active layer thickness, but behaves wave-like, which induces the corresponding variation of *JSC*. The carrier lifetime also inffuence *JSC* greatly. When the carrier lifetime is long enough, dissociation probability will play a very important role for a thicker active layer. *JSC* will behave wave-like with the variation of active layer thickness. When the carrier lifetime is too short (drift length is

P3HT:PCBM layer thickness keeps constant of 208 nm.

**4.2.2 Optimization of annealing conditions** 

be well controlled.

**5. Conclusion** 


**2** 

**AB** 

*1Algeria 2Tunisia* 

**A New Guide to Thermally Optimized** 

**Solar Cells: The Amlouk-Boubaker** 

**Optothermal Expansivity** 

*Mohamed Boudiaf- USTOMB, POBOX 1505 Mnaouer- Oran, 2Unité de Physique des dispositifs à Semi-conducteurs UPDS, Faculté des Sciences de Tunis, Campus Universitaire 2092 Tunis,* 

K. Boubaker2, M. Amlouk2 and A. Amlouk2

M. Benhaliliba1, C.E. Benouis1,

**Doped Oxides Monolayer Spray-Grown** 

*1Physics Department, Sciences Faculty, Oran University of Sciences and Technology* 

PVC Photovoltaic solar cells are unanimously recognized to be one of the alternative renewable energy sources to supplement power generation using fossils. It is also recognized that semiconductors layered films technology, in reducing production costs,

Despite the excellent achievements made with the earliest used materials, it is also predicted that other materials may, in the next few decades, have advantages over these front-runners. The factors that should be considered in developing new PVC materials

Silicon-based cells as well as the recently experimented polymer and dye solar cells could hardly fit all these conditions. Transparent conducting oxides as ZnO, SnO2 as well as doped

In this context, the optothermal expansivity is proposed as a new parameter and a guide to

In spite of better performance of traditional junction-based solar cells, during the past few decades, reports have appeared in literature that describe the construction of cells based metal-oxides (Bauer et al., 2001; Sayamar et al., 1994; He et al., 1999; Tennakone et al., 1999;

optimize the recently implemented oxide monolayer spray-grown solar cells.

**2. Solar cells technologies and design recent challenges** 

**1. Introduction** 

include:

should rapidly expand high-scale commercialization.

 Band gaps matching the solar spectrum Low-cost deposition/incorporation methods

Non toxicity and environmental concerns,

oxides could be good alternative candidates.

Abundance of the elements

