Interdigitated back‐contact heterojunction solar cell concept for liquid phase crystallized thin‐film silicon on glass. (6th December 2015) - Sonntag, Paul
Abstract : We present a back‐contact silicon heterojunction system for liquid‐phase crystallized absorbers on glass. For structuring interdigitating p‐type and n‐type contact areas, etch selectivity of alkaline solutions for n‐doped and p‐doped amorphous Si was used. The cells feature Al or ITO/Ag electrodes. Electrical and optical properties were compared. Including an a priori conducted KOH texture, a jSC value of 30 mA/cm 2 with ITO/Ag compared with 24 mA/cm 2 for planar Al could be achieved, while VOC over 600 mV are feasible with both. Abstract: We present an interdigitated back‐contact silicon heterojunction system designed for liquid‐phase crystallized thin‐film (~10 µm) silicon on glass. The preparation of the interdigitated emitter (a‐Si:H(p)) and absorber (a‐Si:H(n)) contact layers relies on the etch selectivity of doped amorphous silicon layers in alkaline solutions. The etch rates of a‐Si:H(n) and a‐Si:H(p) in 0.6% NaOH were determined and interdigitated back‐contact silicon heterojunction solar cells with two different metallizations, namely Al and ITO/Ag electrodes, were evaluated regarding electrical and optical properties. An additional random pyramid texture on the back side provides short‐circuit current density (jSC ) of up to 30.3 mA/cm 2 using the ITO/Ag metallization. The maximum efficiency of 10.5% is mainly limited by a low of fill factor of 57%. However, the high jSC, as well as VOC values of 633 mV and pseudo‐fill factors of 77%, underline the high potential of this approach. Copyright © 2015 John Wiley & Sons, Ltd.