Defects are intrinsically related to the performance of solar cells.  In solar cells the generation and collection of charge carriers determines their efficiency.  Effective transport of charge carriers across interfaces and minimization of their recombination in the bulk or at surfaces and interfaces is of utmost importance.  In this talk we will discuss the role of surface defects. Surface passivation is very important in limiting the rate of carrier of recombination.  Here we will combine spectroscopic evaluation of the surface of a Si device with electrical lifetime measurements to ascertain what factors determine the quality of a solar cell passivation.  The ability of quinhydrone dissolved in methanol to electrically passivate hydrogen-terminated silicon surfaces with respect to minority carrier recombination has been confirmed. The relative importance of the p-benzoquinone component of quinhydrone has been found to be the active agent.  It is the presence of the ketones on opposite sides of the phenyl ring that works to passivate the surface, although the exact mechanism is under investigation.  The passivation appears to include more than merely repairing damage, such as oxidation, on the hydrogen terminated silicon surfaces.  One hypothesis is that the p-benzoquinone reacts with the surface to create charged sites.  The Coulombic repulsion between the carrier and the charged site would then limit recombination.  Elucidation of this mechanism provides the opportunity to prepare a high-efficiency induced-junction solar cell built on organic/silicon surface chemistry.

Silicon/organic interfaces:    The role of surface defects and their minimization in photovoltaics

244th National Meeting (2012)

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