Oxygen‐alloyed poly‐Si passivating contacts for high‐thermal budget c‐Si heterojunction solar cells. (29th September 2021)

• Record Type: Journal Article
• Authors: Yang, Guangtao; Han, Can; Procel, Paul; Zhao, Yifeng; Singh, Manvika; Mazzarella, Luana; Zeman, Miro; Isabella, Olindo
• Is Part Of: Progress in photovoltaics. Volume 30:Number 2(2022)
• Page Start: 141
• Page End: 151
• Publication Date: 2021-09-29
• Subjects: c‐Si solar cells -- high passivation quality -- low absorption coefficient -- oxygen‐alloyed poly‐Si; Solar cells -- Periodicals; Photovoltaic cells -- Periodicals; Solar power plants -- Periodicals; 621.31245
• DOI: 10.1002/pip.3472
• Languages: English
• ISSNs: 1062-7995

Abstract

Abstract: Crystalline silicon solar cells with passivating contacts based on doped poly‐Si exhibit high optical parasitic losses. Aiming at minimizing these losses, we developed the oxygen‐alloyed poly‐Si (poly‐SiO x ) as suitable material for passivating contacts. From passivation point of view, poly‐SiO x layers show excellent passivation quality and carrier selectivity for both n ‐type (i V OC, flat = 740 mV, contact resistance ρ c = 0.7 mΩ/cm 2, i V OC, textured = 723 mV) and p ‐type (i V OC, flat = 709 mV, ρ c = 0.5 mΩ/cm 2 ). Optically, due to the incorporation of oxygen, the absorption coefficient of poly‐SiO x becomes much lower than that of doped poly‐Si at long wavelength. Both n ‐type and p ‐type poly‐SiO x layers are concurrently deployed in front/back‐contacted (FBC) solar cells with a front indium tin oxide (ITO) layer to facilitate the lateral transport of carriers and minimize cell's reflection. A high cell FF of 83.5% obtained in double‐side flat FBC solar cell indicates an efficient carrier collection by these passivating contacts. An active‐area cell efficiency of 21.0% featuring J SC, EQE = 39.7 mA/cm 2 is obtained in front‐side textured poly‐SiO x FBC cell, with the potential of further improvement in both V OC and FF . The optical advantage of poly‐SiO x over poly‐Si as passivating contact is also observed with a 19.7% interdigitated back‐contacted (IBC) solar cell endowed with poly‐SiO x emitter and back surface field. Compared to the reference 23.0% IBC solar cell with poly‐Si passivating contacts, the one based on poly‐SiO x passivating contacts shows higher IQE at wavelengths above 1100 nm. This indicates that for both FBC and IBC cells, poly‐SiO x passivating contacts hold potential in enhancing the cell J SC by maximizing the cell spectral response. Abstract : With the aim of minimizing the optical parasitical absorption of the poly‐Si passivating contacts for the c‐Si solar cells, both n+ and p+ poly‐SiO x passivating contact alloys were developed and evaluated. Excellent passivation quality and carrier selectivity for both n ‐type (i V OC, flat = 740 mV, contact resistance ρ c = 0.7 mΩ/cm 2, i V OC, textured = 723 mV) and p ‐type (i V OC, flat = 709 mV, ρ c = 0.5 mΩ/cm 2 ) are achieved. The solar cell results, obtained in both 21.0% front/‐back‐contacted (FBC) and 19.7% interdigital back‐contacted (IBC) solar cells, demonstrate the optical and electrical advantages of the poly‐SiO x as passivating contacts for c‐Si solar cells.