High throughput screening of novel tribromide perovskite materials for high-photovoltage solar cells

An efficient search for numerous novel mixed perovskite materials for high-performance solar cells leads to a strong demand for high throughput screening protocols. Highly efficient composition screening based on high throughput fabrication of discontinuous rather than compact perovskite films with comparable properties, which can save plenty of time and effort required for optimizing dense films and can significantly expand the applicability of the screening method to various perovskite compositions, has seldom been investigated. Especially, tribromide perovskites (∼2.3 eV bandgap) with promising applications in tandem and spectral splitting devices require the efficient screening of new constituents to yield a high open-circuit voltage (V_oc). Herein, we develop a highly efficient composition screening protocol based on high throughput inkjet printing of discontinuous perovskite films with representative and comparable properties to accelerate the discovery of novel tribromide perovskites for high-photovoltage solar cells. 30 tribromide perovskite films with similar bandgaps are speedily and automatically inkjet-printed, and a very close grain size is acquired for all samples via optimizing the crystallization. Therefore, the corresponding photoluminescence (PL) lifetime database allows the efficient screening and identification of new constituents for high-photovoltage devices. To validate this, among the 30 samples, two compositions (HC(NH₂)₂)_0.4(CH₃NH₃)_0.6PbBr₃ (FA_0.4MA_0.6) and (HC(NH₂)₂)_0.1(CH₃NH₃)_0.9PbBr₃ (FA_0.1MA_0.9) with a long and short average PL lifetime, respectively, are screened out for device comparison. As expected, the FA_0.4MA_0.6 device delivers a high V_oc of 1.60 V with a champion efficiency of 9.25%, which is among the highest reported V_oc values for tribromide devices, much higher than that (1.45 V and 6.62%) of the FA_0.1MA_0.9 counterpart. Surprisingly, the V_oc limit for both devices is determined to be as high as 2.01 V for the first time. The V_oc and efficiency improvements principally result from the reduced trap states, lower level of energetic disorder, more efficient charge transport and decreased charge recombination losses. Additionally, the validity of the PL lifetime database is further confirmed by a high V_oc of 1.55 V obtained for another novel composition. These findings open up a new avenue for accelerated discovery of new perovskites for advanced device applications.