Direct sputtering of a single quaternary Cu(In,Ga)Se₂ (CIGS) target without postselenization is a promising approach to fabricating CIGS absorbers. However, the device efficiency of the quaternary-sputtered CIGS is limited to 10%–11% due to the low and uncontrollable Se supply during the quaternary sputtering process. Here, an enhanced efficiency of 14.1% is reported by directly sputtering from a CIGS target without extra Se supply followed by sequential postdeposition treatments (PDT) of NaF and KF. The effects of different post-treatments of alkali metals on quaternary-sputtered CIGS thin films are discussed in detail. A Cu-depleted surface is not observed in the quaternary-sputtered CIGS thin films after KF-PDT, different from the observation in the coevaporated CIGS, in which the Cu-depleted surface layer induced by KF-PDT enhances the efficiency. On the other hand, it is found that KF-PDT reduces Se vacancies more effectively than NaF-PDT, which could be another electrically benign behavior of KF-PDT. The effective passivation of Se vacancies after KF-PDT overcomes the Se-poor nature of the quaternary sputtering process without postselenization. Therefore, KF-PDT combined with Na doping, which is known to annihilate In_Cu defects, significantly improves minority carrier lifetime and cell performance.

中文翻译：

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通过碱金属的后处理而无需后硒化的直接溅射Cu（In，Ga）Se2吸收剂的效率超过14％

单四元Cu（In，Ga）Se _2的直接溅射（CIGS）目标而没有后硒化是制造CIGS吸收体的一种有前途的方法。但是，由于在四元溅射过程中硒的供给很少且无法控制，因此四元溅射CIGS的器件效率被限制在10％–11％。在此，通过直接从CIGS靶溅射而无需额外的Se供给，随后依次进行NaF和KF的后沉积处理（PDT），据报道效率提高了14.1％。详细讨论了碱金属的不同后处理对季溅射CIGS薄膜的影响。在KF-PDT之后的四元溅射CIGS薄膜中未观察到Cu贫化的表面，这与共蒸发CIGS中的观察不同，在后者中，由KF-PDT诱导的Cu贫化的表面层提高了效率。另一方面，发现KF-PDT比NaF-PDT更有效地降低了Se空位，这可能是KF-PDT的另一种电良性行为。KF-PDT之后，Se空位的有效钝化克服了四元溅射工艺中的Se贫乏特性，而没有后硒化。因此，KF-PDT与Na掺杂相结合，已知会Na灭In_铜缺陷极大地改善了少数载流子的寿命和电池性能。