**6. References**


have much better elastic properties and high prospects for improving the optical and electrical parameters, and therefore they can be potential solar cells layers. Further experiments are planned for development of manufactured structure (including incorporation of main metal contacts) and manufacturing of thin-film cells with carbon nanotube emitter contacts. However, CNT composites obtain higher optical permeability at a lower carbon nanotubes content, which in turn, increases the resistivity of these materials. Thus, the simultaneous increasing of the permeability and reducing the

Flexible solar cells, based on thin film heterostructure are expected to be a natural development of currently produced devices. For elaboration of fully functional photovoltaic structure, ready for industrial production, many technological problems must be solved. Presented work is a small part of impact put in this process. It is highly probable that some of presented concepts will soon find the implementation in the commercially available

[1] K. Zweibel "Thin Films: Past, Present, Future" Progress in Photovoltaics, Special Issue on

[2] O. Mah "Fundamentals of photovoltaic materials" National Solar Power Research

[3] A. Hepp et al. "Ultra-Lightweight Hybrid Thin-Film Solar cells: A survey of Enabling

[5] D. Bonnet, H. Rabenhorst "New results on the development of a thin film p-CdTe/n-CdS

[6] X. Wu, J. Keane, R Dhere, C. DeHart, A. Duda, T. Gessert, S. Asher, D. Levi, P. Sheldon

European Photovoltaic Solar Energy Conference, Munich 2002 pp 995-1000.

[8] A. Tiwari "Flexible solar cells for cost effective electricity. High efficiency flexible solar

[10] J. Perrenoud, B. Schaffner, L. Kranz, S. Buecheler, A. Tiwari "Flexible CdTe thin film

[11] M. Sibiński, M. Jakubowska, K. Znajdek, M. Słoma, B. Guzowski "Carbon nanotube

Technologies for Space Power Applications" Proc. 5th International Energy Conversion Engineering Conference and Exhibit (IECEC) St Louis 2007 p 4721. [4] V. Bemudez, A. Moreau, N. Laurent, L. Jastrzebski "Roadmap of characterization

techniques for the development of thin film photovoltaic technology" Proc. Photovoltaic Technical Conference – Thin Film 2010, Aix-en-Provence, France

heterojunction solar cell" Proc. 9th IEEE Photovoltaic Specialist Conference, New

"16.5% efficiency CdS/CdTe polycrystalline thin film solar cell" Proc. 17th

cells based on CIGS and CdTe" Proc. Photovoltaic Technical Conference – Thin

solar modules" Proc. Photovoltaic Technical Conference – Thin Film 2010, Aix-en-

transparent conductive layers for solar cells applications", Proc. 10th Electron

resistivity is a difficult issue.

**6. References** 

2010.

elastic cells, based on II-VI compounds.

Thin Films, NREL 1995.

Institute 1998 pp 1-10.

York 1972 pp 129-131.

[9] V. Fthenakis, EMRS-2006 Spring meeting

Provence, France 2010.

[7] ZSW Press Release 05/2010, Stuttgart, Germany 2010.

Film 2010, Aix-en-Provence, France 2010.

Technology Conf. ELTE 2010 and 34th International Microelectronics and Packaging IMAPS-CPMT Conf., 22-25.09, 2010, 81-82.


**13** 

*Jadavpur, Kolkata,* 

*India* 

**Computer Modeling of Heterojunction with** 

**Intrinsic Thin Layer "HIT" Solar Cells:** 

**Sensitivity Issues and Insights Gained** 

*Energy Research Unit, Indian Association for the Cultivation of Science,* 

Despite significant progress in research, the energy provided by photovoltaic cells is still a small fraction of the world energy needs. This fraction could be considerably increased by lowering solar cell costs. To achieve this aim, we need to economize on the material and thermal budgets, as well as increase cell efficiency. The silicon "**H**eterojunction with **I**intrinsic **T**hin layer (HIT)" solar cell is one of the promising options for a cost effective, high efficiency photovoltaic system. This is because in "HIT" cells the P/N junction and the back surface field (BSF) layer formation steps take place at a relatively low temperature (~200°C) using hydrogenated amorphous silicon (a-Si:H) deposition technology, whereas in normal crystalline silicon (c-Si) cells the wafer has to be raised to ~800°C for junction and BSF layer formation by diffusion. This means not only a lower thermal budget, but also cost reduction from thinner wafers, since the danger of the latter becoming brittle is strongly reduced at lower (~200°C) temperatures. Thin intrinsic layers on either face of the c-Si substrate, effectively passivate c-Si surface defects, which would otherwise degrade cell performance. Moreover it has been demonstrated that carriers can pass through the passivating layers

In this chapter, we use detailed electrical-optical modeling to understand carrier transport in these structures and the sensitivity of the solar cell output to various material and device parameters. The global electrical - optical model "Amorphous Semiconductor Device Modeling Program (ASDMP)", originally conceived to simulate the characteristics of solar cells based on disordered thin films, and later extended to model also mono-crystalline silicon and "HIT" solar cells (Nath et al, 2008), has been used for all simulations in this chapter. The model takes account of specular interference effects, when polished c-Si wafers

One of the successful applications of hydrogenated amorphous silicon (a-Si:H) is in crystalline silicon heterojunction (HJ) solar cells. Fuhs et al (1974) first fabricated heterojunction silicon solar cells, where the absorber is P (N) type c-Si, while the emitter N

are used, as well as of light-trapping when HIT cells are depositd on textured c-Si.

**2. Historical development of HIT solar cells** 

**1. Introduction** 

without significant loss.

Antara Datta and Parsathi Chatterjee

[30] Y. Seunghyup, Y. Changhun, H. Seung-Chan and C. Hyunsoo "*Flexible/ ITO-free organic optoelectronic devices based on versatile multilayer electrodes*" – Raport Integrated Organic Electronics Lab (IOEL)Dept. of Electrical EngineeringKorea Advanced Institute of Science and Technology (KAIST), Daejeon, Korea 2009.
