Industrially feasible casting-mono crystalline solar cells with PECVD AlO<inf>x</inf>/SiN<inf>x</inf> rear passivation stack towards 19.6% efficiency

Abstract

Cost reduction and efficiency gain are the maj or goals of research and development in crystalline silicon solar cell technology. Casting-mono crystalline silicon produces higher cell efficiencies compared to multi-crystalline silicon material with the same average minority carrier lifetime and with a similarly low production cost. Aluminum oxide provides excellent passivation on crystalline solar cell and has received great research interests in recent years due to combination of chemical passivation and field-effect passivation provided by a large amount of fixed negative charges. In particular, deposition of AIO, using ALD or PECVD in PERC structure has been well studied. PECVD is preferred for its fast deposition rate. Our research shows that PECVD AIO, films indeed show good passivation quality on casting-mono wafers, which can achieve more than 200l1s average lifetime, 700mV implied Voc and with good stability. Combined with the laser ablation to realize the PERC structure, the PECVD-AIO, contributes to a 12mV increase in Voc compared to the AI-BSF cell. The final cell efficiency reached 19.4% in average with a batch size of 30 wafers and 19.6% for the best cell. Additionally, PECVD AIO, can be easily integrated with the current industrial production line at no significant additional cost. INDEX TERMS: Casting-mono crystalline silicon, PECVD AIO" Passivation.

Enhancement of Light Emission from Silicon by Precisely Tuning Coupled Localized Surface Plasmon Resonance of a Nanostructured Platinum Layer Prepared by Atomic Layer Deposition

“…Thus, one can deduce that enhancement does not originate from charge transfer between the nano-Pt layer and Si (chemical enhancement). The Al 2 O 3 thickness dependence of the minority carrier lifetime shown in Figure 4 is consistent with the previous works reported by Sun et al 42 and Saint-Cast et al 43 When the Al 2 O 3 spacer thickness is below 10 nm, an increase of the minority carrier lifetime with the spacer thickness can be attributed to a decrease in the interfacial state density, i.e., the so-called chemical passivation effect. On the other hand, the presence of a net positive oxide charge in the Al 2 O 3 layer can account for a decrease of the minority carrier lifetime with a spacer thickness greater than 10 nm, due to an increase in the minority carrier (electron) concentration in p-type Si near the interface caused by a positive oxide charge in Al 2 O 3 .…”

Passivated Emitter and Rear Cell Silicon Solar Cells with a Front Polysilicon Passivating Contacted Selective Emitter

“…Passivated emitter and rear cell (PERC) silicon solar cell had kept the efficiency record for over ten years [1] and started to be transferred from laboratory to industry at the beginning of 2010. [2][3][4][5][6] The main improvement of PERC is rear-side passivation compared with aluminum back surface field (Al-BSF) silicon solar cells. At the initial stage of industrialization of PERC cells, it has little cost advantage over Al-BSF cells because of high cost of new materials (mainly trimethylaluminum [TMA]).…”

Effect of Sub-Grains and Crystal Defects on Monolike Si Solar Cell Performance

“…There has been significant progress in monolike cell technology in the past few years. Cell efficiency of ~20% has been reported for the monolike cells fabricated with standard cell processing techniques [4]. It is anticipated that the efficiency of monolike cells can be further improved after optimizing cell processes [5].…”