Identification of the mechanism responsible for the boron oxygen light induced degradation in silicon photovoltaic cells

Abstract

Silicon solar cells containing boron and oxygen are one of the most rapidly growing forms of electricity generation. However, they suffer from significant degradation during the initial stages of use. This problem has been studied for 40 years resulting in over 250 research publications. Despite this, there is no consensus regarding the microscopic nature of the defect reactions responsible. In this paper, we present compelling evidence of the mechanism of degradation. We observe, using deep level transient spectroscopy and photoluminescence, under the action of light or injected carriers, the conversion of a deep boron-di-oxygen-related donor state into a shallow acceptor which correlates with the change in the lifetime of minority carriers in the silicon. Using ab initio modeling, we propose structures of the BsO2 defect which match the experimental findings. We put forward the hypothesis that the dominant recombination process associated with the degradation is trap-assisted Auger recombination. This assignment is supported by the observation of above bandgap luminescence due to hot carriers resulting from the Auger process.

Electrical Characterization of Thermally Activated Defects in n-Type Float-Zone Silicon

“…However, the above analysis assumes that the dominant defect levels are among the ones detected by the DLTS/MCTS; this might not be true. For example, in the case of boron-oxygen related defect responsible for light induced degradation of lifetime in Czochralski grown boron doped silicon wafers, the recombination defect level has not been reliably detected by DLTS, even though the defect has strong recombination activity as detected by lifetime measurements [53].…”

Kinetic Monte Carlo for Process Simulation: First Principles Calibrated Parameters for BO2

“…The events needed to form the BO 2 complex, are the diffusion of isolated O i atoms, their agglomeration in molecular O 2i and the formation of BO 2 . Hence, four species have to be implemented in the KMC code: O i , O 2i , B s O 2i and B i O 2i , where B s O 2i and B i O 2i respectively refer to a BO 2 complex in which the boron atom is in a substitutional [5] and interstitial site [6].…”

Smart systems for the protection of ecosystems, flora and fauna

“…Una conciencia colectiva, basada en criterios de sostenibilidad, que promueva la reforestación y disminución/mitigación de emisiones de calor y elementos contaminantes al ambiente, como forma de remediación ambiental para proteger el hábitat de los animales y todos los seres vivos, con un esquema como el presentado en la Tabla 2. Se plantea un estudio en el comportamiento de interacción de los fotones y enlaces de los materiales constructivos del panel fotovoltaicos [13], para la regeneración de propiedades fotovoltaicas, arquitectura inteligente para ampliar la eficiencia. Energía Térmica-FV Tecnología de recuperación de calor y CO 2 Bancos de calor [14] Captación o recuperación del calor ambiental para uso de la energía térmica reciclada.…”