Dear Ajayakumar,

Let me first thank Remi for his valuable answer. From my point of view, your question needs many posts to cover its answer from different point of views. Let me try to answer it from the point of view of a semiconductor engineer.

The Poisson equation, the continuity equations, the drift and diffusion current equations are considered the basic semiconductor equations. They are used to solve for the electrical performance of the electronic devices upon applying stimuli  on them. This stimuli is in form of voltages or photons or thermal energy. This means by using these equations we can calculate the electrical performance of the devices and derive I-V relations for them. So, they form the theoretical  basis for analyzing and interpreting the the measured performance of such devices.They can also be used to predict the performance of new device structure without going to the very costly experimental work, and therefore they make great saving in effort and cot. By facilitating the mathematical analysis they can be used to get the optimum parameters of the device structure.

These equations are then a very powerful theoretical analysis tool.

Their physical significance is lying in:

- The equations themselves are a sort of a suitable mathematical formulation of the basic physical laws. The phyical laws themselves are experimental laws describing the behavior of the material on different Stimuli like force and energy.

- These equations in their differential form describe the local microscopic behavior of the material. The Poisson equation expresses the local change of the electric field due to the the volumetric charge density  in a location xyz .in the material. The continuity equations express the conservation of electrons and holes in the location xyz. The currents of the electrons and holes are either driven by an electric field in case of the drift current or by a concentration gradient in case of diffusion current.

Solving these equations in predetermined macroscopic device region with the relevant boundary conditions gives us The potential distribution, the electron distribution and the hole distribution. In this way we can get the electron current and the hole current at any proper cross section.

These equations can be solved analytically and get a closed form solutions. An example is the very famous Shockley pn junction diode equation and the famous Shockley theory for transistors. In many cases however, one has to solve these equations numerically. There exists powerful Device simulators that serve as virtual device factory. The results coming out of these device simulator  agree quantitatively to a great extent to the experimental results thanks to the more accurate knowledge about the semiconductor parameters as the mobility and lifetime.

Now, you can imagine  the life of the semiconductor people without these equations in both physical understanding and mathematical formulation.

Thank you for you question.

Dear Ajayakumar,

Let me first thank Remi for his valuable answer. From my point of view, your question needs many posts to cover its answer from different point of views. Let me try to answer it from the point of view of a semiconductor engineer.

The Poisson equation, the continuity equations, the drift and diffusion current equations are considered the basic semiconductor equations. They are used to solve for the electrical performance of the electronic devices upon applying stimuli  on them. This stimuli is in form of voltages or photons or thermal energy. This means by using these equations we can calculate the electrical performance of the devices and derive I-V relations for them. So, they form the theoretical  basis for analyzing and interpreting the the measured performance of such devices.They can also be used to predict the performance of new device structure without going to the very costly experimental work, and therefore they make great saving in effort and cot. By facilitating the mathematical analysis they can be used to get the optimum parameters of the device structure.

These equations are then a very powerful theoretical analysis tool.

Their physical significance is lying in:

- The equations themselves are a sort of a suitable mathematical formulation of the basic physical laws. The phyical laws themselves are experimental laws describing the behavior of the material on different Stimuli like force and energy.

- These equations in their differential form describe the local microscopic behavior of the material. The Poisson equation expresses the local change of the electric field due to the the volumetric charge density  in a location xyz .in the material. The continuity equations express the conservation of electrons and holes in the location xyz. The currents of the electrons and holes are either driven by an electric field in case of the drift current or by a concentration gradient in case of diffusion current.

Solving these equations in predetermined macroscopic device region with the relevant boundary conditions gives us The potential distribution, the electron distribution and the hole distribution. In this way we can get the electron current and the hole current at any proper cross section.

These equations can be solved analytically and get a closed form solutions. An example is the very famous Shockley pn junction diode equation and the famous Shockley theory for transistors. In many cases however, one has to solve these equations numerically. There exists powerful Device simulators that serve as virtual device factory. The results coming out of these device simulator  agree quantitatively to a great extent to the experimental results thanks to the more accurate knowledge about the semiconductor parameters as the mobility and lifetime.

Now, you can imagine  the life of the semiconductor people without these equations in both physical understanding and mathematical formulation.

Thank you for you question.

A very big thanks Prof. Abdelhalim Zekry, really it is amazing answer to  my question,

I would like to know more about in the treatment of organic semiconductor materials

Dear Ajayakumar,

The basic semiconductor equations are applicable for macroscopic semiconductors in general.The Poisson equation is applicable for any material. The continuity equations are based on the mass and charge conservation in a closed systems. The drift current and the diffusion current describes the flow rates of the electrons and holes in a semiconductor whenever the electric field and concentration gradient exists.

What changes is the semiconductor parameters such as the doping, the mobility, the diffusion coefficient, and the recombination mechanisms.

In case of microscopic devices, one has to consider the quantum mechanical equations.For more information, to prove the applicability of the semiconductor equations on organic material follow the Link:

http://www.sciencedirect.com/science/article/pii/S1566119903000235

and the Link:

http://mitran-lab.amath.unc.edu:8081/subversion/PolymerPhotovoltaic/C-ChargeTransport/biblio/Giebink2010.pdf

Wish you success

Thank you so  much Prof.Abdelhalim Zekry , Really I got good information.

Thank you once again

really its very useful. Thank u Sir Prof. Abdelhalim Zekry

Thank you so much great Prof.Abdelhalim Zekry for your wonderful answer.

You are really so much helpful.

Thank you so much sir  Prof.Abdelhalim Zekry for your wonderful answer.

super like for this wonderful answer Prof.Dr.Abdelhalim Zekry .GOD bless you.

Thank you so much Prof.Abdelhalim Zekry

Thank you so much for these fundamental, wonderful explanations Prof.Dr.Abdelhalim Zekry.

To all friends and colleagues

When i spend time for answering questions you made it very fruitful my dear friends and colleagues. You compliments is the best acknowledgement that a researcher can get in his life. I who must thank you for these wonderful kind words that made me happy.

Best wishes