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Performance Study of the Micromorph Silicon Tandem Solar Cell Using Silvaco TCAD Simulator
摘要： This paper is concerned with the numerical modelling of a micromorph silicon tandem solar cell (a-Si:H/μc-Si:H), under series (two-terminal: 2T) and independent (four-terminal: 4T) electrical connection. The study is performed using the simulation software Silvaco TCAD. Both the initial (un-degraded or annealed) state, and the light induced degradation one (well-known Staebler–Wronski effect in a-Si:H) are considered for the studied solar cell, operating under the standard global solar spectrum (AM1.5G). The 2T- and 4T-device optimization is carried out under the effects of the intrinsic (i)-layer thickness of the two sub-cells, and the free carrier mobilities through these layers. By increasing the i-layer thickness of the two sub-cells, the 2T-micromorph tandem cell reveals an optimal conversion efficiency ?? of 10% and 7.77% corresponding, respectively, to the initial and degraded states. The 4T-configuration exhibits a relatively better ?? of 10.94% at initial state, reduced only to 9.59% at the degraded one. Further improvement of the 2T and 4T-cell output parameters is obtained by increasing the free carrier mobilities, particularly through the top-cell i-layer. By this way, the better ?? is also ensured by the 4T-device, which displays an initial state-?? of 12.31%, reduced only to 11.43% at the degraded state. However, the improved efficiencies reached by the 2T-configuration are 11.87% and 10.41% corresponding, respectively, to the initial and degraded states.
关键词： Numerical simulation,Micromorph,Tandem solar cell,μc-Si:H,a-Si:H
更新于2025-09-11 14:15:04
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Wide band-gap Cu <sub/>2</sub> SrSnS <sub/>4</sub> solar cells from oxide precursors
摘要： Recent progress in the efficiency of Cu2ZnSnS4 (CZTS) solar cells has been relatively slow due to severe bulk band tailing issues that have proven difficult to resolve. Band tails in CZTS are caused by defect-related potential fluctuations, as diagnosed by the large shift between the CZTS band gap and its photoluminescence (PL) peak. In this work, we demonstrate that the PL-band gap shift can be decreased roughly by a factor of 5 when Zn is replaced by the heavier cation Sr. The resulting Cu2SrSnS4 compound is of considerable interest for photovoltaics due to its sharp band edges and suitable band gap (1.95-1.98 eV) for a top absorber in tandem cells. Trigonal CSTS thin films are synthesized in this work by sulfurization of strongly Cu-poor co-sputtered Cu2SrSnO4 precursors. The first functioning CSTS solar cells are demonstrated, even though the very high conduction band of CSTS implies that the typical CdS/ZnO electron contact of CZTS solar cells must be redesigned to avoid large voltage losses.
关键词： tail states,tandem solar cell,sputtering,wide band-gap absorber,Kesterite,cation substitution,potential fluctuations
更新于2025-09-11 14:15:04