N-type boron emitter solar cells with implantation industrial process

Abstract

The use of ion implantation for PV application could be an innovative way of developing advanced cell structures with respect to a very simple fabrication process. Its application on p-type silicon solar cells has already showed its potential with the achievement of efficiency above 19% with selective emitter structure [1]. Nevertheless, the development of more complexes architectures like the ntype boron emitter is even more promising as the fabrication process would remain simple and the cell efficiency could be significantly improved. This study is dedicated to the achievement of high quality boron implanted emitter on textured surface. Very low emitter saturation current densities (J0e) of 80fA/cm² with implied Voc of 665mV were reached. The influence of the thermal treatment was also investigated for P-implantation. Large area solar cells (148.6cm²) on n-type Cz substrates were fabricated by co-annealing boron emitter and phosphorous BSF respectively at the front and back side of the cell. This fabrication process only requires nine processing steps which lead to a much simpler process than the conventional one made by means of single side gas diffusion. Finally, efficiencies of 16.9% were obtained with relatively poor open-circuit voltage and short-circuit current. Detailed characterization indicates a poor emitter quality which is not consistent with the saturation current density obtained on symmetrical samples. The impact of the thermal budget on the electrical properties of the wafers was investigated.

Effective passivation of p+ and n+ emitters using SiO2/Al2O3/SiNx stacks: Surface passivation mechanisms and application to industrial p-PERT bifacial Si solar cells

“…In recent years, researchers have put a lot of efforts also into PERT cells, especially on industrial aspects. Most of them have been carried out using ntype Czochralski (Cz) Si to take advantage of the high bulk minority carrier lifetime (τb) present conventionally in n-type substrate [17][18][19][20][21][22][23][24][25][26][27][28][29]. However, this technology faces challenges in mass production due to high cost and low utilization of the n-Si material.…”

“…Hoex developed n-PERT (ηcell=23.2%) with Al2O3 passivated front B -emitter in 2008 [31], which was updated with ηcell=23.9% (n-PERL cell) in 2010 by S.Glunz [32]. In recent years, researchers have devoted efforts into PERT towards industry, most of which were carried out using n-type Cz-Si to take advantage of the high τb [17,18,[27][28][29][19][20][21][22][23][24][25][26]. During ~ 2010-2015, Suniva [20,24,26], B OSCH Solar [21,28] and LG electronics were the leading companies working on the industrial n-PERT.…”

“…Regarding Bimplanted junction, most of the previous research is focused on lab-scale [17,22,[42][43][44][45][46][47][48][49], which are mostly carried out using lab-scale implanters combined with complex lab-scale cell processes. Although there are promising studies considering the industry aspects as well [23][24][25][26][27]181,182] there is still a need for more systematic study on the implanted B -junctons and solar cell properties. Such study is needed to implement the cost-efficient roadmap consisting of fully ion-implantation and screen-printing technologies.…”

Boron Implanted Junction with In Situ Oxide Passivation and Application to p‐PERT Bifacial Silicon Solar Cell

“…However, with the recent development on more cost‐efficient implanter by several suppliers (Varian, Intevac, Kingston), a second fast‐developed period for ion‐implanted PV occurred in 2010s, generating a promising progress for the phosphorus (P)‐doped implantation technique and industrial full Al BSF Si solar cells . Regarding the B‐implanted junction, most of the previous research is carried out using lab‐scale implanters combined with complex lab‐scale cell processes but there are also promising studies considering the industry aspects as well …”

“…Bifacial cells have demonstrated a good potential due to the bifacial generation of electricity combined with relatively low cost. Up to now, most research of bifacial cells has been carried out on n‐type Czochralski Si (Cz‐Si) to take advantage of the high bulk minority carrier lifetime ( τ b ) . However, this technology faces challenges for mass production due to high cost and low utilization of the n‐Si material.…”