High-efficiency solar cell by combining high and low thermal budget for Si passviting contacts

Abstract

Various parameters including optimal surface passivation, carrier selectivity, and low recombination losses are prerequisite for high efficiency in silicon heterojunction solar cells. Herein, the surface passivation quality of crystalline silicon solar cells is improved by a hybrid passivation structure including a silicon heterojunction contact at the front side and a stack of tunneling oxide with n-type nano-crystalline silicon oxide (nc-SiOx(n)) passivating contact at the rear side. In our study, Initially, a low-temperature, energy-efficient, electron-selective hetero-contact was fabricated by using a hydrogenated intrinsic amorphous silicon (a-Si:H(i)) layer as the front surface. Secondly, the poly-silicon layer swapped with nc-SiOx(n) layer to improve the effective surface passivation, electrical properties, and carrier selectivity. The passivation properties of symmetric structures were optimized, and the Boron doped amorphous silicon (a-Si:H(p))/a-Si:H(i) showed a lifetime (τeff) of 1.6 ms and implied open-circuit voltage (i-Voc) of 719 mV, respectively. On the other hand, the nc-SiOx(n)/SiO2 stack shows a τeff of 2.1 ms and i-Voc of 725 mV respectively. The optimized passivated layers were used for the fabrication of hybrid solar cell and showed the performance as; Voc = 724 mV, Jsc = 38.95 mA/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , FF of 75.9%, ŋ= 21.4%.