TY - JOUR

T1 - Direct Examination of the Deactivation of the Boron–Oxygen Center in Cz-Si Solar Cells Under Regeneration Conditions via Electroluminescence

AU - Helmich, Lailah

AU - Walter, Dominic C.

AU - Schmidt, Jan

N1 - Funding Information: Manuscript received April 2, 2019; revised May 29, 2019; accepted June 25, 2019. Date of publication September 2, 2019; date of current version October 28, 2019. This work was supported by the German State of Lower Saxony and the German Federal Ministry of Economics and Energy within the Research Project “Upgrade Si-PV” under contract no. 0325877B. (Corresponding author: Lailah Helmich.) L. Helmich and J. Schmidt are with the Institute for Solar Energy Research Hamelin, D-31860 Emmerthal, Germany, and also with the Department of Solar Energy, Institute of Solid-State Physics, Leibniz University of Hannover, D-30167 Hannover, Germany (e-mail: l.helmich@isfh.de; j.schmidt@isfh.de).

PY - 2019/9/2

Y1 - 2019/9/2

N2 - We examine the regeneration kinetics of the boron-oxygen defect in boron-doped p-type Czochralski-grown silicon (Cz-Si) solar cells as a function of the excess carrier concentration Δn at the regeneration conditions, i.e., at elevated temperature (140 °C). To perform the regeneration, we apply different forward-bias voltages (V appl) to solar cells in darkness and measure directly the emitted electroluminescence (EL) signal at different time steps during the regeneration of the cell. Measuring the EL signal emitted by the solar cell during regeneration, we are able to directly determine Δn during regeneration for each applied voltage. In addition to the EL signal, we measure the electric current flowing through the solar cell during the regeneration process. This current is proportional to the overall recombination rate in the cell and, hence, reflects the changing bulk recombination during the regeneration process. From the measured time-dependent cell current, we determine the deactivation rate constant R de of the boron-oxygen defect. Our experimental results unambiguously show that R de increases proportionally with Δn during the regeneration process.

AB - We examine the regeneration kinetics of the boron-oxygen defect in boron-doped p-type Czochralski-grown silicon (Cz-Si) solar cells as a function of the excess carrier concentration Δn at the regeneration conditions, i.e., at elevated temperature (140 °C). To perform the regeneration, we apply different forward-bias voltages (V appl) to solar cells in darkness and measure directly the emitted electroluminescence (EL) signal at different time steps during the regeneration of the cell. Measuring the EL signal emitted by the solar cell during regeneration, we are able to directly determine Δn during regeneration for each applied voltage. In addition to the EL signal, we measure the electric current flowing through the solar cell during the regeneration process. This current is proportional to the overall recombination rate in the cell and, hence, reflects the changing bulk recombination during the regeneration process. From the measured time-dependent cell current, we determine the deactivation rate constant R de of the boron-oxygen defect. Our experimental results unambiguously show that R de increases proportionally with Δn during the regeneration process.

KW - Boron-oxygen defect

KW - Czochralski-grown silicon

KW - carrier injection

KW - electroluminescence (EL)

KW - light-induced degradation (LID)

KW - passivated emitter and rear cells (PERCs)

KW - regeneration

UR - http://www.scopus.com/inward/record.url?scp=85077516879&partnerID=8YFLogxK

U2 - 10.1109/jphotov.2019.2926855

DO - 10.1109/jphotov.2019.2926855

M3 - Article

VL - 9

SP - 1472

EP - 1476

JO - IEEE journal of photovoltaics

JF - IEEE journal of photovoltaics

SN - 2156-3381

IS - 6

M1 - 8822456

ER -