Wallace Choy1 Wei E.I. Sha1 Hong Zhang1 Zi Shuai Wang1 Hugh L. Zhu1 Xingang Ren1

1, University of Hong Kong, Hong Kong, , China

Due to interesting features of direct band gap, high and balanced carrier mobility, long electron-hole diffusion length, low non-radiative Auger recombination, and high internal quantum efficiency, perovskite solar cells (PVSCs) have been consideration as the great potential candidate for the next-generation high-performance photovoltaics. Various approaches have been proposed to improve device performances, and enhance power conversion efficiency (PCE) up to 22%. However, limited works discuss the loss mechanism and quantify the efficiency loss for perovskite solar cells.
In this work, we will unveil the loss mechanism and quantify the loss factors of perovskite solar cells. Through investigating the device performance of various fabricated perovskite solar cells, the three dominant loss factors of optical loss, non-radiative recombination loss, and ohmic loss are identified quantitatively. The perovskite-interface induced surface recombination, ohmic loss, and current leakage are also analyzed. Our theoretical and experimental results show that for experimentally optimized perovskite solar cells with the power conversion efficiency of 19%, optical loss of 25%, non-radiative recombination loss of 35%, and ohmic loss of 35% are the three dominant loss factors for approaching the 31% efficiency limit of perovskite solar cells. We also find that the optical loss will climb up to 40% for a thin-active-layer design. Moreover, a misconfigured transport layer will introduce above 15% of energy loss. Finally, the perovskite-interface induced surface recombination, ohmic loss, and current leakage should be further reduced to upgrade device efficiency and eliminate hysteresis effect. Consequently, the work offers a guideline to the researchers for optimizing perovskite solar cells and ultimately approaching the Shockley-Queisser limit of photovoltaics [1].

[1] W.E.I. Sha#, H. Zhang#, Z.S. Wang, H.L. Zhu, X. Ren, F. Lin, A.K.-Y. Jen, W.C.H. Choy*, Adv. Energy Mater., in press.