Solar cells based on organometal trihalide perovskites (eg. CH3NH3PbI3) as light absorbers are emerging as a low-cost and high performance photovoltaic technology that may fulfil the requirement for large-scale deployment of solar energy. Over the past few years, significant progress was made in pervoskite solar cells with power conversion efficiencies (PCE) shot up from 3% to 18%. Recent studies revealed that organometal trihalide pervoskites exhibit several desired properties for photovoltaic applications including facile tunable bandgaps, high absorption coefficient, long carrier-diffusion lengths, high ambipolar mobilities and low exciton binding energy, making them a very appealing class of material for new generation photovoltaic technology.
In this talk I will present two strategies to improve the performance of perovskite/organic planar heterojunction solar cells. First, the growth kinetic of the perovskite films was tuned by introducing chemically-tailored processing additives. Depending on the choice of the additives, the crystallinity and coverage of the perovskite films can either be enhanced or suppressed and we found that the solar cell performance was strongly depending on the morphology of the perovskite films.[1,2] Second, novel interfacial materials were introduced to improve the contact between the fullerene electron transport layer and the metal cathode interface, resulted in Ohmic contact with reduced interfacial resistance and a significant improvement on the fill factor. We will also discuss a new strategy to design novel electron transporting conjugated polymers as efficient electron selective interlayer for fullerene-free hybrid pervoskite solar cells. Combining these two strategies high performance perovskite solar cells with over 15% PCE were achieved.[3]
Reference:
1. Q. Xue, Z. Hu, C. Sun, Z. Chen, F. Huang, H.-L. Yip and Y. Cao, RSC Adv., 2015, 5, 775.
2. C. Sun, Q. Xue, Z. Hu, Z. Chen, F. Huang, H.-L. Yip and Y. Cao, Small, in press.
3. Q. Xue, Z. Hu, J. Liu, J. Lin, C. Sun, Z. Chen, C. Duan, J. Wang, C. Liao, W. M. Lau, F. Huang, H.-L. Yip, Y. Cao, J. Mater. Chem. A, 2014, 2, 19598