Silicon heterojunction solar cells can employ p-type hydrogenated nanocrystalline silicon nc-Si:H(p) on their front side, since these can provide better transparency and contact resistance compared to hydrogenated p-type amorphous silicon layers. We investigate here the influence of trimethyl boron (TMB) and BF3 as dopant source on the layer properties and its performance in solar cells. Both gases enable high efficiencies but yield a different crystallinity and effective doping. A high BF3 flow lowers the series resistance through a low activation energy of dark lateral conductivity and maintains a high crystallinity. This allows fill factors up to 83%, however with the apparition of a parasitic absorption in the UV. A low TMB flow enables simultaneously a high crystallinity and a low activation energy. As an illustration of this layer potential, a 23.9%-certified efficiency is achieved with a 2 × 2 cm2 screen-printed device. We finally suggest that similar transport versus transparency trade-offs can be reached for both dopant types for front junction application, while high BF3 flow allowing lower series resistance might be of interest when placed on the rear side.

中文翻译：

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P型纳米晶硅层中掺杂气体前驱体对前结异质结太阳能电池性能的影响


硅异质结太阳能电池可以在其正面采用p型氢化纳米晶硅nc-Si:H(p)，因为与氢化p型非晶硅层相比，它们可以提供更好的透明度和接触电阻。我们在此研究了三甲基硼 (TMB) 和 BF3 作为掺杂剂源对太阳能电池层特性及其性能的影响。两种气体都能实现高效率，但会产生不同的结晶度和有效掺杂。高 BF3 流量通过暗横向电导率的低活化能降低串联电阻并保持高结晶度。这使得填充因子高达 83%，但会出现紫外线中的寄生吸收。低 TMB 流量可同时实现高结晶度和低活化能。作为该层潜力的例证，2 × 2 cm2 丝网印刷器件实现了 23.9% 的认证效率。最后，我们建议，对于前结应用的两种掺杂剂类型，可以实现类似的传输与透明度权衡，而当放置在后侧时，允许较低串联电阻的高 BF3 流量可能会令人感兴趣。