Presented by:- Nayanee Singh B.Tech(E.C.), 5 th sem Roll no: Banasthali University Rajasthan

 Introduction  Organic devices: Materials  Types of OSC  Principle of operation  working of OSC  Organic vs. inorganic solar cell  Applications  Limitations  Future aspects of OSC  Conclusion  References

 Organic solar cell is a polymer solar cell that uses organic electronics for light absorption and charge transport to produce electricity from sunlight by photovoltaic effect.  The small molecules and polymers used to make Organic solar cell have large conjugated system.  Photon absorbtion creates an excited state i.e. excitons.

 Organic material used are:- CN-PPV( Cyano Polyphenylene Venylene) PPV( phenylene vinylene) pthalocycnine MEH-PPV(Poly[2- methoxy-5-(2- ethylhexyloxy)-1,4- phenylenevinylene] ) Fig: Organic materials

 The types of OSC are:-  Single layer Organic solar cell  Bilayer Organic solar cell  Bulk heterojunction Organic solar cell  Graded heterojunction Organic solar cell

 Organic material is sandwiched between two metallic conductors.  Metallic conductors have different work function which produce electric field in organic layer.  Very low efficiency Fig: Single layer organic solar cell

 Two different layers sandwiched between metallic conductor.  Two layers of material have difference in electron affinity and ionisation energy.  Layer with high electron affinity is electron acceptor and other layer is electron donor  Due to large thickness of junction than diffusion length of excitons, efficiency is low Fig: bilayer organic solar cell

 Electron acceptor and donor mixed together, forming polymer blend.  Length of polymer blend is same as exciton diffusion length.  Efficiency is improved.  Heterojunction mainly consists of conductive polymers and fullerenes. Fig : Bulk heterojunction organic solar cell

 Electron acceptor and electron donor are mixed together like in bulk heterojunction but the gradient is gradual.  This architecture combines the short electron travel distance with the advantage of charge gradient in bilayer technology which improves the efficiency.

Anode Electrode Cathode Electrode 1.Absorption of a photon 2.Formation of an exciton 3. Diffusion of the exciton 4.Charge transport Organic material Fig: in single layer organic solar cell LUMO (Lowest unoccupied molecular orbital) HOMO (Highest occupied molecular orbital )

 The difference of work function between the two conductors sets up an electric field in the organic layer. When the organic layer absorbs light, electrons will be excited to the LUMO and leave holes in the HOMO, thereby forming excitons.  The potential created by the different work functions helps to separate the exciton pairs, pulling electrons to the positive electrode and holes to the negative electrode. The current and voltage resulting from this process can be used to do work

 INORGANIC  Inorganic material like Si is used to manufacture inorganic solar cell  Light absorbtion leads to the formation of free electron-hole pair.  High manufacturing cost and rate of converting solar energy into electricity  High efficiency  ORGANIC  Organic material like pthalocyanine is used  Light absorbtion leads to the formation of Excitons  Low manufacturing cost and are very cheap  Low efficiency

 Low absorbtion coefficient than organic solar cell  Inorganic material properties cannot be altered to fit for any application  Heavy and rigid  High absorbtion coefficient  Molecular engineering can change the properties of the organic material in order to fit for the application  Light in weight and flexible so, less prone to damage

 Research in U.S. (konarka) has shown that organic cells can be used in soldiers tents to generate electricity and supply power to other military equipments such as GPS receivers  Portable battery chargers  Electric car chargers  Office and residential power  Renewable and portable energy  satellites

 Organic solar cell have low efficiency than inorganic solar cells, representing a big point of weakness at present  More susceptible to oxygen and water  Short life span because sunlight continuously destroy the organic material used  Temperature variations cause degradation and decreased performance over time  Strong columbic force of attraction between excitons is responsible for the complexity in the generation of free electrons and holes, affecting photocurrent

 Development of environment friendly devices  Another possibility would be to combine solar cells, sensors and electronic circuits on a small strip of plastic to form a self-sufficient power Microsystems  organic photovoltaic materials that can be made or processed in liquid form, allowing them to be applied to a wide array of surfaces  Light weight and flexible organic solar cells can be printed over cloths

 Organic cell offer to provide an eco-friendly, large area flexible solar cell technology at low production cost.  There is always a trade-off between cost and efficiency, OSC have low efficiency but are cost effective. So, OSC’s are more economic to use.  They are the cheaper alternative of inorganic solar cell and in future main focus will be on increasing its efficiency and operating stability.  Although it faces the limitations like low efficiency, stability problem etc. but still It has the potential to be a part of world’s solution to the future of energy.

  nic-photovoltaics-the-good-the-bad-and-the-inefficient nic-photovoltaics-the-good-the-bad-and-the-inefficient  organic-solar-photovoltaic-market.htmlhttp:// organic-solar-photovoltaic-market.html  Brian A. Gregg and Mark C. Hanna, “Comparing organic to inorganic photovoltaic cell: Theory, experiment and simulation”, journal of applied physics, volume 93, number 6, year  Pankaj Kumar and Suresh Chand, “Recent progress and future aspects of organic solar cells”, Centre of organic electronics, National Physical Laboratory, New Delhi, 2011  Scott Berkley, “The Fabrication and characterisation of organic solar cells”, may, 2009

THANK YOU