High efficiency silicon solar cells with PECVD dielectric rear surafce passivation - HIGHPOINT

该项目的目标是开发一种新设计的单晶硅太阳能电池的工业化生产工艺，效率在20%以上，电池面积为150cm2，可以高成本地大批量生产。太阳能电池结构将包括高效率的前接触激光沟槽掩埋接触工艺，以及最先进的等离子体增强化学气相沉积(PECVD)非晶态二氧化硅/碳化物/氮化物系列中的低温介质薄膜，从而产生钝化的背面。金属触点将通过自对准电镀工艺形成。这些改进将在工业规模上进行演示，并将验证在光伏系统水平上降低20%成本的潜力。为了实现硅(Si)晶片良好的表面钝化，我们将要研究的薄膜是氢化非晶硅(a-Si：H)及其含碳(a-SiC：H)和氮(a-SiN：H)的合金。A-SIN：H涂层现在是光伏行业中各种太阳能电池的标准涂层，从由多晶硅晶圆制造的低效率设备到SunPower Corp.(美国加州)和三洋(日本)制造的非常高效率(&gt；22%)太阳能电池。此外，a-Si：H层被用于新型高效异质结太阳能电池设计，例如三洋HIT电池。A-SiC：H薄膜在硅片基器件中受到的关注明显较少，更多地被用于薄膜光伏组件中。这清楚地表明了a-Si：H合金在增强各种光伏器件性能方面的兼容性。NaREC目前的激光沟槽埋栅(LGBG)技术导致太阳能电池表现出比其能力更差的性能，而且LGBG太阳能电池正在失去曾经在该领域占据的竞争优势。NAREC已经仔细地优化了LGBG太阳能电池的正面，然而，让它失望的是设备的背面/特别是在对近红外光的响应方面。因此，在Highpoint研发项目中，我们的目标是利用a-Si：H薄膜合金的能力来增强LGBG太阳能电池背面的表面钝化。此外，新颖的是，我们还将设计Highpoint太阳能电池，使其与NaREC的化学镀金属方法(同时在正面和背面形成选择性金属接触)兼容，同时不破坏a-Si：H薄膜的钝化性能。如果成功，这将使Highpoint太阳能电池实现20%(绝对值)的转换效率，同时保持与大批量制造兼容的简单太阳能电池结构。

The project aim is to develop an industrial production process for a new design of monocrystalline silicon solar cells with an efficiency above 20% on a cell area of 150 cm2 which can be manufactured cost effectively in high volume. The solar cell structure will comprise the high efficiency front contact laser grooved buried contact process together with state of the art plasma enhanced chemical vapour deposition (PECVD) of low temperature dielectric films in the amorphous silicon dioxide/carbide/nitride family producing a passified rear surface. The metal contacts will be formed by a self-aligning plating process. The improvements will be demonstrated at an industrial scale and the potential for a 20% reduction in cost at the PV system level will be verified. The thin films we will be investigating for achieving good surface passivation of silicon (Si) wafers are based on hydrogenated amorphous silicon (a-Si:H) and its alloys with carbon (a-SiC:H) and nitrogen (a-SiN:H). A-SiN:H coatings are now standard in the PV industry for a wide range of solar cells / ranging from lower-efficiency devices fabricated from multicrystalline silicon wafers to the very high-efficiency (> 22%) solar cells manufactured by SunPower Corp. (CA, USA) and Sanyo (Japan). In addition, a-Si:H layers are used in novel high-efficiency heterojunction solar cell designs such as the Sanyo HIT cell. Films of a-SiC:H have received significantly less attention for wafer-based Si devices, being used more commonly in thin-film PV modules. This clearly indicates the compatibility of a-Si:H alloys for enhancing the performance of a wide variety of PV devices. NaREC's current laser-groove buried-grid (LGBG) technology is resulting in solar cells that exhibit a poorer performance than they are capable of, and they are LGBG solar cells are losing the competitive advantage they once held over the field. NaREC have carefully optimised the front side of the LGBG solar cell, however it is the rear-side of the device that is letting it down / particularly in its response to near-infrared light. Therefore, in the HIGHPOINT R&D project we aim to capitalise on the ability of a-Si:H thin film alloys to enhance the surface passivation at the rear of the LGBG solar cell. Furthermore, what is novel is that we will also engineer the HIGHPOINT solar cells to be compatible with NaREC's electroless metal plating method (for simultaneously forming selective metal contacts on both the front and rear) while not destroying the passivating properties of the a-Si:H films. If successful, this will enable the HIGHPOINT solar cells to achieve a conversion efficiency of 20% (absolute), while maintaining a simple solar cell structure that is compatible with high-volume manufacturing.