STRUCTURE FOR IMPROVING THERMAL STABILITY OF BULK HETEROJUNCTION SOLAR CELLS AND RELATED PHOTOVOLTAIC APPARATUS AND METHOD FOR MAKING THE SAME

摘要

A bulk heterojunction solar cell comprises an electron donor, an electron acceptor, and a multi-substituted fullerene derivative. The electron acceptor further comprises a nano-scale electron acceptor material, and a meso-scale mixture of electron donor/acceptor material. The multi-substituted fullerene derivative further comprises a single fullerene structure and a multi-substituted derivative connected to the single fullerene structure. The multi-substituted fullerene derivative is utilized to prevent the meso-scale mixture of electron donor/acceptor material from large-scale segregation of acceptor over a specific temperature after a specific period (thermally unstable state), thereby maintaining the thermal stability and the sizes of the nano-scale acceptor material and meso-scale mixture of electron donor/acceptor material. In the conventional knowledge, the large-scale segregation and corresponding degradation of power efficiency are cause mainly by the nano-scale acceptor material. The work shows the control and role of meso-scale structure is the most critical.