Effects of electron-and hole-current hysteresis on trap characterization in organo-inorganic halide perovskite

Charge trap density and carrier mobility of perovskite materials are the critical properties of perovskite solar cells.The space charge limited current(SCLC)method,which measures a dark current–voltage(I-V)curve of a single-carrier device has found extensive use for studying the trap density and charge carrier mobility in perovskite materials.Herein,it was found that the electron-and hole-current in organo-lead perovskite-based single-carrier device undergoes significant hysteresis under forward and reverse scanning due to the mobile ions.In addition,it was also observed that measuring history has a detrimental effect on hysteresis resulting in possible overestimation or underestimation of the extracted electrical values from the SCLC measurement.In the forward/reverse scanning process,the mobile ionic defects enhance/shield the charge in the traps due to ionic charging/discharging,thereby increasing/reducing the interface barrier and net charge in the I-V scanning,which in turn affects the determination of transport properties of the carrier.These results raise quite a few doubts over the direct application of classical SCLC measurements for the accurate characterization of intrinsic transport properties of the mixed ionicelectronic perovskite.

Strategies for high-performance perovskite solar cells from materials, film engineering to carrier dynamics and photon management

In recent years,halide perovskite solar cells(HPSCs)have attracted a great atten-tion due to their superior photoelectric performance and the low-cost of processing their quality films.In order to commercialize HPSCs,the researchers are focusing on developing high-performance HPSCs.Many strategies have been reported to increase the power conversion efficiency and the long-term stability of HPSCs over the past decade.Herein,we review the latest efforts and the chemical-physical principles for preparing high-efficiency and long-term stability HPSCs in particu-lar,concentrating on the perovskite materials,technologies for perovskite films,charge transport materials and ferroelectric effect to reduce the carrier loss,and photon management via plasmonic and upconversion effects.Finally,the key issues for future researches of HPSCs are also discussed with regard to the require-ments in practical application.