Interdigitated back-contacted silicon heterojunction solar cells using semi-industrial processing equipment

Abstract

Interdigitated back-contacted a-Si:H/c-Si heterojunction solar cells were made using two different approaches for patterning the a-Si:H layers: screen-printing in combination with wet chemical etching and in-situ mechanical masking. Processing was restricted to semi-industrial, low cost processing equipment on 6" wafers, cut back after processing into nine smaller cells by laser. After active layer patterning, implied V OC values of over 700 mV were measured for both approaches and the best J SC and V OC values on cell level were 39.7 mA/cm 2 and 697 mV, respectively. Efficiencies over 21% are expected, when some metallization issues at the rear are solved.Index Terms -amorphous silicon, crystalline silicon, heterojunction, interdigitated back-contacted solar cells.

Emitter Patterning for Back-Contacted Si Heterojunction Solar Cells Using Laser Written Mask Layers for Etching and Self-Aligned Passivation (LEAP)

“…While for metallization industry-proven screen printing techniques are in principle available, there is still a need for the development of a cost-effective and reliable heterocontact patterning technology for SHJ solar cells. Several approaches have been presented in the past years, employing either mechanical shadow masks [2], [11], [12] or metallic hard masks [13], as well as printing techniques using etch resists [14] or etch pastes [15]. The above-mentioned techniques have been developed mainly to simplify processing of back-contact cells by avoiding photolithographic steps.…”

“…However, they still usually require separate patterning process steps for forming oppositely doped areas, including an alignment step. This holds also for patterning techniques where a dielectric layer is used as a mask [15] in combination with layer openings made using etch paste, or in combination with laser-based layer opening [16]. For comparison, in emitter patterning technologies for diffused junction cells, patterned dielectric mask layers are employed for self-aligning during a subsequent full area deposition step.…”