Metal halide perovskite solar cells are now effectively competing with their inorganic counterparts in terms of power conversion efficiencies and estimated production costs. State of the art perovskite solar cells still suffer from too low fill factor and open circuit voltage (V_oc), which has been related to non-geminate losses mostly happening at the surface of the perovskite absorber.  Here,  we present  the  enhancement  of  the  V_oc   by  addition  of  Strontium  (Sr)  to  a  quadruple cation  perovskite  Rb₅(Cs₅(MA_0.17FA_0.83)Pb(I_0.83 Br_0.17)₃)₉₅)₉₅  in  a  p-i-n  solar  cell structure with PTAA and C₆₀  forming the  hole and  electron  transport  layer,  respectively. When alloying the perovskite with Sr, the resulting material displays significantly enhanced PL lifetime and absolute PL yield. This indicates a reduction of surface recombination thereby enlarging the splitting of the quasi-Fermi-levels in the neat perovskite absorber, giving promise for a increased V_oc in the device. This finding is confirmed by the enhancement in V_oc and in electroluminescence efficiency observed in actual devices, where the V_oc increase from 1.11 V to 1.18 V and electroluminescence efficiency rises up by one order of magnitude upon Sr addition, denoting impressing emissive behaviour.  As a result, the power conversion efficiency increases by up to 1% (absolute), reaching a PCE of 20.3% under AM1.5G illumination. We  show  through  various photoelectron  spectroscopy  techniques (UPS/XPS  and  IPES), how the addition of Sr changes the energetic  landscape, inducing a more n-type surface and enabling a  more  electron selective contact between the perovskite and the  C₆₀. We propose that such  a  change  in  energetics  is  responsible  for  a  substantial  suppression  of  surface recombination in the neat material and a reduction of interface recombination with the electron transport layer (ETL). Through Secondary Ion Mass Spectroscopy (SIMS), XPS and Scanning Electron Microscopy (SEM) we show that Sr is mostly segregated close to the charge transport layers, affecting only the interface and leaving the bulk almost unaltered. In conclusion, we propose that Sr-addition enables an appropriate  interface  modification  between  the  perovskite  and  the  charge transport  layers that helps  to  suppress  surface  recombination  and  reduce V_oc  losses.  Our  results  can  be  representative  of  a  more  general methodology  for  device  modification,  therefore  they  can  be  applicable  to  other compositions  and  cell  architectures  enabling  future  efficiency  enhancements  of perovskite solar cells.