Luc Fesquet

Efficient Monolithic Perovskite/Silicon Tandem Solar Cell with Cell Area >1 cm2

Monolithic perovskite/crystalline silicon tandem solar cells hold great promise for further performance improvement of well-established silicon photovoltaics; however, monolithic tandem integration is challenging, evidenced by the modest performances and small-area devices reported so far. Here we present first a low-temperature process for semitransparent perovskite solar cells, yielding efficiencies of up to 14.5%. Then, we implement this process to fabricate monolithic perovskite/silicon heterojunction tandem solar cells yielding efficiencies of up to 21.2 and 19.2% for cell areas of 0.17 and 1.22 cm(2), respectively. Both efficiencies are well above those of the involved subcells. These single-junction perovskite and tandem solar cells are hysteresis-free and demonstrate steady performance under maximum power point tracking for several minutes. Finally, we present the effects of varying the intermediate recombination layer and hole transport layer thicknesses on tandem cell photocurrent generation, experimentally and by transfer matrix simulations.

Modification of textured silicon wafer surface morphology for fabrication of heterojunction solar cell with open circuit voltage over 700 mV

Crystalline silicon wafer (c-Si) can be extremely well passivated by plasma enhanced chemical vapor deposited (PECVD) amorphous silicon (a-Si:H) films. As a result, on flat substrates, solar cells with very high open circuit voltage are readily obtained. On textured substrates however the passivation is more cumbersome, likely due to the presence of localized recombinative paths situated at the pyramid valleys. Here, we show that this issue may be resolved by selecting a silicon substrate morphology featuring large pyramids. Chemical post-texturization treatments can further reduce the surface recombination velocity. This sequence has allowed us to fabricate solar cells with open circuit voltage over 700 mV, demonstrating also on device level the effect of pyramid density and surface micro-roughness on the surface passivation quality.

Towards a better understanding of silicon heterojunction solar cells

Note: IMT-NE Number: 526 Reference PV-LAB-CONF-2010-034 Record created on 2010-02-01, modified on 2017-05-10