Abstract
Crystalline silicon (c-Si) is the dominating photovoltaic technology today, with a global market share of about 90%. Therefore, it is crucial for further improving the performance of c-Si solar cells and reducing their cost. Since 2014, continuous breakthroughs have been achieved in the conversion efficiencies of c-Si solar cells, with a current record of 26.6%. The great efficiency boosts originate not only from the materials, including Si wafers, emitters, passivation layers, and other functional thin films, but also from novel device structures and an understanding of the physics of solar cells. Among these achievements, the carrier-selective passivation contacts are undoubtedly crucial. Current carrier-selective passivation contacts can be realized either by silicon-based thin films or by elemental and/or compound thin films with extreme work functions. The current research and development status, as well as the future trends of these passivation contact materials, structures, and corresponding high-efficiency c-Si solar cells will be summarized.
Highlights
A negatively charged dipole should exist at the transition metal oxides (TMOs)/n-Si interface, which results in a shift of the energy band and makes the carrier internal force of carrier separation in crystalline silicon (c-Si) dopant-free asymmetric heterocontacts (DASH) solar cells have not been clearly understood [60,61], even though their conversion efficiencies are higher than 20% [40]
These results further indicate that the high high work function of TMO is critical to improving the performance of TMO/Si solar work function of TMO is critical to improving the performance of TMO/Si solar cells
This article presents the latest advances in highly efficient c-Si solar cells with passivation contacts, including doped silicon films and dopant-free materials, with a high/low work function
Summary
Severe energy crises and environmental problems increasingly promote the rapid research and development of the photovoltaic industry [1,2,3]. Recent studies indicated that carrier recombination loss via defect states, present at the contact points between the absorber and the metal, become the key factor for further improving conventional diffused homojunction c-Si solar cell efficiency [13,14]. Such recombination losses decrease the fill factor (FF), and the open-circuit voltage (Voc ), and result in a lower device efficiency. To resolve the contact-recombination issue caused by metal–semiconductor contact, further investigation into advanced contact schemes and/or device structures is necessary
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