Session 3C – Photovoltaics Reliability/ESREF Best Paper

Session 3C – Photovoltaics Reliability/ESREF Best Paper

Photovoltaics Reliability Session Chairs: Andrea Cester, University of Padova , Michael Daenen, University of Hasselt
Section F/G

1:55 p.m. – Session Introduction

2:00 p.m.

3C.1 Predictive Simulation of Defect Migration and Metastabilities in CdTe Solar Cells

D. Guo, R. Akis, D. Brinkman, D. Vasileska, A. Moore*, Arizona State University, *Colorado State University

Performance of CdTe solar cell, similarly to performance of any other semiconductor device is uniquely defined by device geometry and properties of semiconductor regions such as band parameters, distribution and parameters of doping and trapping/recombination centers. However, when the above variables cannot be measured precisely, predictive simulation of device performance becomes rather challenging, and CdTe PV devices exemplify such situation. Moreover, predictive simulation of CdTe devices becomes even more challenging due to low temperature diffusion and reaction of Cu-related centers, phenomena that is known to strongly affect the device causing both short-term metastabilities and permanent changes in device performance. In this work, we present a self-consistent diffusion-reaction simulation scheme that was developed to overcome these challenges by accurate simulation of electrically active centers in the device structure, and the evolution of these centers under stress conditions to support our hypotheses that explains rapid changes in atomic concentration of Cu in CdTe as function of stress conditions.

2:25 p.m.

3C.2 Effects of Current Stress and Thermal Storage on polymeric heterojunction P3HT:PCBM Solar Cell

A. Rizzo, A. Cester, L. Torto, M. Barbato, N. Wrachien, N. Lago, M. Corazza*, F. Krebs*, S. Gevorgyan*, University of Padua,*University of Denmark

Polymeric solar cells have attracted the attention of many research groups as a low-cost and eco-sustainable alternative to conventional solar cells [1-2]. In this work, we investigated the effects of accelerated electrical stress in forward bias condition and thermal storage. We employed the Impedance Spectroscopy technique to obtain a more comprehensive picture of the cell degradation phenomena.

2:50 p.m.

3C.3 Improvement of Solar Cell Performance and Reversibility of Ageing Effects in Hydrogenated Amorphous Silicon Solar Cells under Illumination and Electric Field Stress: Role of TCO and Substrate

A. Scuto, M. Foti*, C. Gerardi**, A. Battaglia***, S. Lombardo, IMM CNR, *STMicroelectronics, **Enel Green Power, ***3SUN

In this work we discuss about the hydrogenated amorphous silicon (a-Si:H) photovoltaic improvement performance caused by the application of an external electric fields to the cells under illumination. The effects, clearly visible on the series resistance, on the open circuit voltage, and on the overall power conversion efficiency have been investigated discussing the key impact of tempera-ture, electric field intensity and illumination level. Showing the evident reversibility effects visible in complete solar cells, but also in individual doped a-Si:H thin films, we demonstrate that such phenomenon is due principally to the motion of some ions/molecular species from the oxide to the a-Si:H films (or vice-versa) driven mainly by the electric field. Finally, to further investigate on the possible species that migrates causing a reduction of recombination current, we discuss some exper-iments based on different substrates analysis, various types of TCO and double-junction/micromorph solar cells comparison.

3:15 p.m.

3C.4 Reconfigurable Power Management for Monolightic CMOS-on-Photovoltaic under Partial and Complete Shading

R. Mahto, P. Zarkesh-Ha, O. Lavrova*, University of New Mexico, *Sandia National Laboratory

The Photovoltaic (PV) cells of a module can be made to operate in various load and lighting condition by using switches to connect in series or parallel for various load requirements in the field, such as high voltage and low current versus high current and low voltage. Compared to having external switches monolithic CMOS-on-PV cells improves the module efficiency by providing better reliability and lifetime. In this paper, a partial and complete shading detection algorithm is presented. Also, a model for calculating the output current and voltage equation for the monolithic CMOS-on-PV cell is presented.


3:40 p.m.

4:10 p.m.

3C.5 System-level Process-voltage-temperature Variation-aware Reliability Simulator using a Unified Novel Gate-delay Model for BTI, HCI and GOBD (ESREF Best Paper)

T. Liu, C.-C. Chen, S. Cha, L. Milor, Georgia Institute of Technology