Breakdown characteristics of flexible Cu(In,Ga)Se2 solar cells

Shading-induced failure in thin-film photovoltaic modules: Electrothermal simulation with nonuniformities

“…(5) compared to data points from (Szaniawski et al, 2013). Reasonable, qualitative agreement with both the voltage and temperature dependence of the data (Szaniawski et al, 2013;Puttnins et al, 2014) is obtained for α = 2 V −1 and α = 4 V −1 for the dark and light cases, respectively. The 'defective' case with lower reverse breakdown voltage and α = 6 V −1 was used for local weak spots in our simulations.…”

“…Given our purpose of studying shading effects, it is essential that the diode IV characteristics have the correct features under reverse bias. Experimentally, reverse breakdown voltages of V br ≈ −4 V in the dark and V br ≈ −2 V in light have been observed in pristine CIGS cells (Szaniawski et al, 2013;Puttnins et al, 2014). That light-enhanced reverse breakdown was found to be most pronounced for blue light rather than red.…”

“…Spatial and temporal variations of current and temperature are calculated to better understand the stresses caused by shading and the concomitant reverse bias. The typically observed (Szaniawski et al, 2013;Puttnins et al, 2014) reverse break-down characteristic of CIGS devices is included in our model and we argue that the presence of low reverse breakdown voltage points (spatial nonuniformity) is a key factor in shading-induced failure. Our results demonstrate an example of thermal instability as a positive feedback mechanism in a nonuniform thinfilm, the physics of which was described in (Karpov, 2012).…”

Photocurrent multiplication in Ga2O3/CuInGaSe2 heterojunction photosensors

“…The signal current saturated at an applied voltage of 3 V, but drastically increased again for applied voltages over 4 V. We think that the cause of this signal multiplication was avalanche multiplication. Avalanche multiplication in a CIGS photodiode was reported by Matsushima et al [25] in 2009 and by Puttnins et al [42] in 2014. Our avalanche multiplication factor was about three when the saturated current was set to unity.…”

Potential of CuS cap to prevent decomposition of Cu2ZnSnS4 during annealing

“…The large increase is very significant, and would, if it accurately reflects the doping in the absorber layer, be expected to have a significant effect on the device behavior. The light activated reverse breakdown observed for sample B and C, may in fact be another indicator of a high‐doping density in these samples, as the breakdown voltage is inversely proportional to the doping density for Zener breakdown . If tunneling is involved in the observed breakdown, the high doping levels could therefore be the reason for the low breakdown voltages.…”