Modelling of Limitations of BHJ Architecture in Organic Solar Cells

Polymer solar cells are considered as very promising candidates for the development of photovoltaics of the future. They are cheap and easy to fabricate, however, up to now, they possess a fundamental drawback: low effectiveness. One ask the question how fundamental this limitation is. We propose the simple model which examines the limitations of efficiency by analysis of geometrical aspects of the bulk heterojunction (BHJ) architecture. We calculate the effective area of the donor-acceptor border in the random mixture of the donor and the acceptor nanocrystals and further compare it with an ideal “brush architecture”. It turns out that in the BHJ architecture, this effective areas are very close to the value obtained in the “brush” one. Implications of this fact are discussed: we consider some other factors, which could limit the efficiency of the BHJ architecture, try to estimate its scale and speculate on possibilities of realization of another architectures and materials in the construction of solar cells.