Electroluminescence transients and correlation with steady-state solar output in solution-prepared CH 3 NH 3 PbI 3 perovskite solar cells using different contact materials

CÓRDOBA, M; CORREA, N; CÓRDOBA, M; CORREA, N; HERRERA, W; PEREZ, M D; HERRERA, W; PEREZ, M D; KOFFMAN-FRISCHKNECHT, A; TARETTO, K; KOFFMAN-FRISCHKNECHT, A; TARETTO, K

JOURNAL OF PHYSICS - D (APPLIED PHYSICS)

IOP PUBLISHING LTD

Año: 2020 vol. 53

0022-3727

Electroluminescence (EL) transients of solution-prepared CH3NH3PbI3 perovskite solar cellswere recorded under different biasing voltage conditions. The EL transients are reversible andshow a sharp increase and a peak in the range of 1 s to 10 s, while after the peak the signaldecays in 30 s to 60 s. The possible origins of the different features are discussed, pointing toa shift in the region of dominating recombination during biasing, governing the EL increase,and the creation of ion migration-induced non-radiative recombination centers during the ELdecrease. Moreover, when ramping up the polarization voltage, the EL transients shorten,suggesting an acceleration of the microscopic mechanism with increasing electric fields. Cellsprepared with compact instead of mesoporous TiO2 electron contact show faster dynamics,highlighting the link between dynamics and interface properties. Furthermore, experimentsusing cells with different hole contacts show that the observed behavior and the duration ofthe transient is similar in cells using Spiro-OmeTAD and copper phatlocyanine (CuPc). Whenconsidering the steady-state EL, the open circuit voltage under solar operation correlates withEL across samples with different HTL materials. A non-monotonous behavior is also observedin temperature-dependent EL transients, where maxima in EL as well as in time to the peakare observed around 30 °C, which is close to the temperature of crystalline phase change fromtetragonal to cubic phase known in CH3NH3PbI3 at 37 °C.