Back Amorphous-Crystalline Silicon Heterojunction (bach) photovoltaic device

Back Amorphous-Crystalline Silicon Heterojunction (BACH) photovoltaic device integrates a range of high efficiency features while using low temperature (~200°C) fabrication processes. High efficiency features include back contact metallization, optimum interfacial passivation, and front-side and rear-side reflective coatings and scatterers for maximum light trapping. Two types of BACH cell prototypes were fabricated in this work with the best performing cell having an AM1.5G conversion efficiency of 8.1%, V_OC = 0.536 V, J_SC = 20 mA/cm² and FF = 75.5%. Theoretically, the BACH solar cell concept has the potential of attaining energy conversion efficiencies in the 20 - 25% range. In this first set of cells, the BACH cell performance is limited by poor surface passivation and un-optimized cell design. Recent experiments with various passivation procedures has led to high minority carrier lifetimes in the ms range while carrying out the processes at low temperature, thus opening the way to higher efficiency BACH cells.